GENERAL CONSIDERATIONS

JUST as the measuring of the skeletal parts differs m many respects from that of measuring the living, so does the measuring of the skeletal and fleshy silhouettes of the roentgenogram of the head differ from either craniometry or cephalometry. Moreover. roentgen ray anthropometry is especially attractive by reason of the cleanliness of the investigation and because, unlike any other branch of anthropologic enquiry, roentgen ray anthropometry offers a field of study heretofore impossible; that of investigating the ectocranium, the endocranium and in great measure the soft coverings of the head; and all these in the living.
In this country the study of physical anthropology may be said to have begun with the researches of the immortal Samuel G. Morton in Philadelphia, in 1830. The historical development of this incident is interesting, and according to Morton himself, the beginning of his actual work in anthropology is related to have occurred as follows:
"Having had occasion, in the summer of 1830, to deliver an introductory lecture to a course in anatomy, I chose for my subject, 'The Different Forms of the Skull as Exhibited in the Five Races of Men.' Strange to say, I could neither buy nor borrow a cranium of each of these races; and I finished my discourse without showing either the Mongolian or the Malay. Forcibly impressed with this great deficiency in a most important branch of science, I at once resolved to make a collection for myself."
With the beginning of anthropological studies in America, as initiated by Morton, it will be observed that attention is directed first to craniology. The cranium is naturally the most interesting and the most important part of the skeleton; and it is no wonder that the preoccupation of anthropology with the skull has been such as to overshadow the study of the rest of the skeleton. Craniometrical methods and instruments have multiplied perhaps a little beyond the actual need. The first earliest summary of this mass of research was made by Broca, Vogt and Topinard, and more recently has been condensed and selected so as to conform with the admitted efforts toward standardization by the Monaco and 322
Geneva Conventions and presented in the two most valuable current contributions to anthropology entitled, respectively, (1 ) "Anthropometry" and (2) "Physical Anthropology," both under the authorship of Dr. Ales Hrdlicka.
Hrdlicka's Anthropometry is the model after which roentgen ray anthropometry is patterned. It will be the aim to parallel such measures and observations enumerated in Hrdlicka's "Anthropometry" as may be obtained from the study of the roentgenogram; to supply, for the same subject, such cephalometric measures and observations as the roentgenogram may provide in accordance with Hrdlicka's standards; and in addition, as nearly as possible to approximate such other useful anthropologic characteristics as may prove of value in the immediate application of roentgen ray anthropometry to clinical studies.
Certain preliminary procedures are considerably important and must necessarily be observed before beginning either a description or measure of the skull. These are included under three general heads, namely, (1) sexing; (2) estimation of the age, and (3) determination of normality.

SEXING

Female crania differ from the male by the same characters which tend to distinguish the female skeleton from the male skeleton. Ecker early remarked on the lesser development of the processes serving for the attachment of the muscles in the skeleton of the female, a process especially perceptible in the mastoid prominence, the temporal and cervical lines, and the ridges on the lower jaw. In the male skull the protuberances of the osseous cavities are more developed, as is seen in the superciliary ridge produced by the bulging of the frontal sinuses. In regard to the size it has always been accepted that the female skull is absolutely smaller than the male skull; Welcker furnished accurate information on this topic in
1862 for the first time. Ecker in 1866 studied the proportion of the cranium to the face as a whole, and that of the separate parts, and concluded that the female cranium presented certain cranio-facial relations that distinguished it from the male cranium. This subject has more recently been revived under the topic of cranio-facial index mentioned by Bean, and will be referred to again later in this thesis.
Topinard remarks that sex can not be recognized with infallible precision from any one character, but is inferred from the study of a group of characters, among which he names the shape of the feminine head, intermediate between that of the infant and adult man; the general gracefulness and fineness; the lesser prominence of the muscular insertions and the bony processes. The following points, says Topinard, should receive preferential attention; the forehead which is, all other things equal, straighter in the female than in the male skull; the superciliary ridges and the glabella, infinitely less developed in the female; the high and horizontal vault of the feminine cranium; the relatively less capacity and weight of the skull; the mastoid arid the styloid processes, both of conspicuously less development in the feminine as compared to the masculine skull; and the massiveness of the zygoma and the alveolar processes, less in the female than in the male.
As Hrdlicka remarks, there are male skulls which in some or all of their features are less masculine than the average; and similarly, there are female skulls that in some or all of their parts resemble the masculine. There is no sharp dividing line, but rather an interdigitation and continuity, as a result of which, in certain cases, the sexual identification of a specimen remains uncertain despite all the efforts of the anthropologist.
Roentgen ray anthropometry introduces the concept of the "summation of sex characters." In roentgen-ray anthropometry, as conducted on the living, the sex is definitely known; and it might appear at first consideration, superfluous, to conduct any observations bearing upon sexual identification. It was observed, however, that in certain types of mental deficients showing strongly developed homosexual traits, that the summation of sexual characters as obtained from a study of the cranial roentgenogram often leads to inferences that were at variance with the true anatomical sex of the individual. It is felt that this observation is fraught with intrinsic potential value in the study of mental deficients from the viewpoint of anthropology; and also that it may lessen the percentage of inferences in the identification of the sex of crania as practiced by the anthropologist who has no way or means for checking the accuracy of his observations.
The instructions given by Hrdlicka for establishing the sexual identification of a cranium are, in summary, as follows: The observer notes first the size of the vault as well as that of the face; a large size steaks normally for a male and the small size for a female. The features observed next and in the order named, are the supraorbital ridges, the mastoids, the zygomata, the occipital crests, the lover jaw, the palate and the teeth, the facial "physiognomy" and the base of the skull.

SIZE
The roenteenogram lends itself to the study of many of these characters, such as the size, the smoothness, the supraorbital ridges, the mastoid process, the zygomata, the angle and the strength or massiveness of the lower jaw. As mentioned previously, Welcker established what had always been accepted, that the female skull is absolutely smaller than the male skull. It is sufficient to record the size of the cranium as revealed upon the roentgenogram according to the following nomenclature:
Size

These terms are purely qualitative and would vary for studies applied to different races; but in a series limited to one race they acquire a snore nearly quantitatiNc value. Arbitrary values have been assigned according to the descriptive terminology; so that a very small bead of any series could be arkitrarily valued as one, and a very large head in that same series would receive a value of five.

SMOOTHNESS

Having observed the size of the head and recorded its arbitrary value, the investigator next examines the smoothness. The smoothness is manifested by the gracefulness of tire cranial curves, by the absence of step?like depressions or elevations along the median sagittal suture, but more especially at the bregma, lambda and tl,c occipital crests. It may be recorded, pursuant to the general method of roentgen ray antbropometry according to the following nomenclature:

SUPRAORBITAL RIDGES

Next in order the supraorbital ridges are studied. On the average these are decidedly more developed in the male than in the female. According to Bianchi, in human crania the spongy tissue of the frontal bone above the nasion becomes absorbed between the sixth and eighth years of age and thus initiates the formation of the frontal sinuses. This is furthered by the evagination into this spongy tissue of the mucous membrane lining the nasal cavity, and by the exertion of this membrane of its osteolytic capacity (McMurrich). According to Sappey, at puberty and after. the sinuses dilate, thus accentuating the glabella and making prominent the superciliary ridges. Mantegazza believes that the sinuses continue to increase in adults and even in the aged. Bianchi established the independent development of the superciliary ridges apart from the simultaneous development of the frontal sinuses:  and it is common experience to note that the congenital absence of frontal sinuses is not necessarily accompanied by absence of the superciliary ridges. The degree of development of the superciliary ridges or supraorbital ridges may be characterized as follows:

It is the rule that pronouncedly or excessively developed su!lraorbital ridges are never observed in the female; neither are ridges that might be classed as "traces" found in adult males. Schaaffhausen attributes the more marked superciliary ridges in man than in woman to the relation which exists between muscular development and the projection of the brows.
Broca traced the superciliary ridges and provided a scale from zero to four, which is here reproduced. It is hot necessary that this scale should be rigorously applied. The terms above employed are adequately descriptive. A supraorbitàl ridge somewhere between number zero and number one of
 

FROM BROCÀS INSTRUCTIONES CRANIOLOGIQUES  ET CUNIOMETRIQUES, PARIS, 1875, (PLANCNE VE AND  RIBBE , TÍ?IESE 97, PARIS ,1885.

Figure IV.?From Broca's "Inetrnctione'Craãiolosiqne9'et Craniombtriqnes"  Paris, 1875, (Planche VI.) and Ribbe, These 97, Paris. 1885. showing a  scale for interpreting suture serration; a scale for qnántitatively recording  suture occlusion; and the degree of protuberance of the snperciliaryr ridaó or alabella.

Broca's four would be called excessive, and a protuberance more marked than Broca's four would be called excessivt. Qualitative degrees between these two would be slight, moderate, medium and pronounced (see Fig. 4).

MASTOID PROCESS

Next in order the study of the development of the mastoid process is important. This process is formed by the posterior extremity of the petrous bone and is relatively small at birth, when it contains no air cells excepting in the antrum. It develops and becomes permeated with cells as age increases. Its development is largely determined by the sternocleidomastoid muscle which inserts into the mastoid process of the temporal bone. Male mastoids are larger than female processes: so that small mastoids do not occur in males, neither do large or excessive mastoids occur in females. In the median sagittal projection of the skull, on the roentgenogram, the mastoid process must be sought with great care, as in this exposure its silhouette is superimposed over the shadow of the bodies of the atlas and axis.
An estimate of the degree of its development is best gained by visually completing the basi-occipital rotundity and noting the size of the triangular silhouette projected by the mastoid process as it extends from this rotundity with its base attached to the occiput and its apex pointing downward and forward. From the length of the basilar attachment to the occiput, and the height of the triangular apex, the size of the mastoid process is accurately judged. The values for the mastoid process are:

ZYGOMATA

Panichi was early impressed by the protuberance of the zygoma, an anatomic entity that had previously attracted the attention of Luschka and one of his disciples, Werfer. Panichi was interested more especially in the study of the zygomatic spines which he described under eight types; and for which he developed an index based on the relation that exists between the height of the pyramidal protuberance and the height of the spine referred to the standard of 100 (height of the pyramidal protuberance : the height of the spine : : 100 : x). Hrdlicka mentions the massiveness of the entire ~ygom° as a criterion useful in the distinction of the sex. Zygomata are recorded as:

Un 'kjs care is exercised in producing the cranial roentgenogram the zygoma (sinistral) is not clearly outlined. The massiveness of the zygomata may be in part inferred from the size of the antrum of Highmore as well as from the distinctness of the outline of the zygomatic arch as it courses backward to the glenoid fossa. Only the most slender zygomata escape definite visualization.
 

MANDIBLE

Morselli in 1875 presented a study on the relation that existed between the weight of th! skull and the mandible; and arrived at the conclusion that the inferior mandible of the male is heavier than that of the female; and that the sexual character of the weight of the mandible is an important craniometric criterion for distinguishing between sexes. Mingazzini, elaborating on the previous work of Sandifort and Meckel, communicated his study on the morphologic significance of the angle of the mandible. When the roentgen ray exposure is made according to the formula outlined in Part I, the projection of the sinistral half of the inferior mandible is moderately distorted owing to ray divergence. Any measures that are to be made may be corrected through the method before prescribed; but these corrections need not be applied if it is desired only to gather a qualitative inference of the degree of angularity or a lack of angularity observed in the mandible. The angularity of the lower jaw, as revealed by the prescribed technique on the roentgenogram, may be recorded as:

In addition to the angularity the massiveness of the jaw is an important criterion. This may be gauged somewhat from the height of the symphysis: but in judging the height, the size and strength of the mandible should at the same time be observed and their value included in the estimate of that for the height, as follows:

For convenience in recording the sex characters of the cranium a roentgen ray anthropologic chart may be prepared according to the copy presented. The chart is devised so as to record the observation on five crania. The characteristics are observed in the proper order, as indicated on the chart, and the value checked opposite the figure in the column for the skull under study. Following the last evaluation, which is that for the height and massiveness of the lower jaw there is a space for recording the total sum of character value; and underneath this the name, age, sex, height, weight, physical condition and clinical diagnosis of the patient are included. (See mimeographed form, page 326).

SEX VALUE

Obviously the most typically feminine skull in a series would present a summation of the lowest value (or each characteristic, which is, according to the scale devised, 7 ; and similarly the most typical male skull in that same series would be represented by the sum of the maximum characteristics, which is 36. These extreme values are seldom observed. The average between the minimum female characteristics, 7, and the maximum male characteristics, 36, affords a mean of 21.5. The figure 21 may be used to represent the critical sex value. Figures above 21 represent dominantly male individuals, and figures below 21, dominantly female.

The application of this study to the roentgenograms of crania of homosexuals has in certain series presented the peculiar finding that the summation of sex character values in some males was found lower, and in some females higher than 21. This is not only of anthropologic interest, but is also clinically significant to the psychiatrist in pointing to the possibility of viewing the homosexual as a phylogenetic entity of óntogenetic misfitness; or to use the words of a leader in psychiatry to whom these observation were presented "roentgen ray anthropometry for the first time affords an accurate means for observing the biologic male in the anatomic dress of the female."

SKULL THICKNESS

On the thickness of the vault much has been written; and it was thought by some, as for instance Schaa((hausen, that most of the skulls of the highest antiquity are distinguished by the thickness of the cranial bone; but this may partly be due to great muscular action, and partly to mode of life, Mhich furnished in some cases an excess of calcium phosphate for the nourishment of the bone. So that thickness of the vault, alone, is of no dec1siNe value in sexual identification.

ESTIMATION OF AGE

A correct estimate of the age from the skeleton is not of extreme anthropologic necessity. Generally it suffices to determine whether the skull is subadult, adult or senile. For these determinations the anthropologist studies the state of fusion of the basilar suture, that of the epiphyses of the long bone, the stage of dentition, the condition of the teeth and alveolar processes, and the state of the sutures of the vault of the skull (Hrdlieka).
In sagittal view, the basi-sphenoidal suture is not roentgenographically visible; so that its occlusion, a sign valuable to the anthropologist, can not be utilized by the roentgenologist. A study of the epiphyses of the long and other bones is possible, though it necessitates additional roentgen ray exposure. Flrdlicka offers the following table, based upon modern anatomical writings, for the ossification of the various epiphyses
 
 

                                                                                                             Year

Based on the roentgenographic study of 30,000 cases, given by Pacini, the ,age of fusion of various epiphyses coincides very closely Nvith the age of those oflcred by Rotch and Morris. The compáratiNc tables are appended. (Tables of Rotch and Morris modified and copied from Holmes and Ruggles, "Roentgen Interpretation.")

I f the study is directed with the immediate aim of definitely ascertaining the age of the subject, careful roentgenography of the various bones and their epiphyses should establish the age within one or two years when the individual is under thirty; but it is seldom necessary or desirable to direct an inquiry entirely (or the estimation of the exact age.

TEETH

The eruption of the temporary and of the permanent teeth is a useful indication of the age of the subject. Deciduous dentition, among whites, is complete usually before the end of the third, and permanent dentition before the thirtieth year of life. A complete set of teeth in a skull is a valuable index pointing to the (act that adult life has

been attained, or nearly attained. Bean gives the following order for the eruption of the permanent teeth:
 
 

From a composite study of Bean, Bednar, Cherot, Gray, Matiegka and others, Hrdlicka furnishes the follow ing data relative to the eruption of temporary and permanent teeth in whites:

CRANIAL SUTURES

The obliteration of the cranial sutures has been used to assist in estimating the age. It is valuable when studied in conjunction with other indication=. The study of cranial sutures is interesting and important, not alone from the viewpoint of age estimation, but also from that of pathology, more especially rickets.
On the roentgenogram of the sagittal ~ icw of the head, excepting in old age, the lambdoid suture is normally visible, and less frequently the coronal suture. 'Fine sagittal suture, because of its lateral projection, can be studied indirectly by noting the contact at Important junctions, such as at the bregma and lambda.
As Ribbe pointed out, the sagittal suture consists of four divisions which from front to back are: (1 ) the bregmatic portion; (2) the vertical portion: (3) the obelion portion; and (4) the paralambdoidal portion. At the bregma there may be an elevation or depression where the sagittal meets the coronal suture; and similarly at the lambda there may be most usually a depression as the occipital bone bulges outward where the sagittal meets the lambdoidal suture. Beyond these remarks the study of the state of fusion of the sagittal suture can be inferred only from the general configuration of the head. In scaphocephaly, in which the sagittal suture is fused, lateral expansion of the vault is interfered with so that the head grows lengthwise in the plane of least resistance; and it assumes the "boat-keel" form characteristically observed in the negro, and in white skulls, and others, where the sagittal suture has early fused as the result of pathology.
Each half of the coronal suture presents three distinguishable portions. These are: ( I ) the bregmatic, (2) the complex, and (3) the occipital. The bregmatic portion is relatively short (Ribbe gives three centimeters as the average length). A great part of the bregmatic portion of the coronal suture is in a more or less horizontal plane and is, therefore, not projected on the roentgenogram of the sagittal view of the head. The complex portion is so named because of the intricacy and length of the tortuous dendrites that compose it. This portion of the coronal suture is more nearly vertical in its position on the cranium and when patulous it is projected onto the roentgenogram. It is practically the only portion of the coronal suture that is all clearly visualized on the roentgenographic plate. The third or temporal portion of the coronal suture is free from serrations and is very compact and linear. It ends at the pterion where it meets the equally compact sphenoidal suture. This portion is rarely observed in a roentgenogram of adolescent or adult crania.
Ribbe similarly divides the lambdoidal suture into three portions. The first he describes as descending four centimeters from the point of its departure from the sagittal suture and as presenting many varieties and modifications. The second portion, like the second portion of the coronal suture, is complicated and intricately serrated. The third portion begins where the second ends and runs, practically rectilinearly and compact to the asterion. When the skull structures are sagitally projected the first portion of the lambdoidal suture is virtually superimposed upon the shadow of the cross section of the occipital bone, and is, therefore, roentgenographically invisible. The second portion of the lambdoidal suture, like the second portion of the coronal suture, is visible in the vast .majority of skull roentgenograms; whereas the third portion, quite similar to the third portion of the coronal suture and for similar reasons, can not be at all defined.
It seems to be generally agreed that in very early life the endocranial structure of the sutures corresponds morphologically to the ectocranial structure; but as age advances the endocranial aspect loses its serrations, straightens and begins to fuse, whereas the ectocranial aspect straightens to a small extent, more generally fusing without much loss in serrated structure. In reporting suture serration as observed on the roentgenogram, the notation introduced by Broca and modified by Ribbe and Zanolli may be employed. Broca, in his principles of craniologic instructions, produced a table of serrations. (See Figure 4). Ribbe says, of Broca's table: "Evidently every degree of possible serration is not represented by one of these five types; one may observe many intermediate types; but these may be easily expressed in terms of the figure immediately lower than the type to be classified, augmented by a fraction representing the degree between the immediate lower figure and the next higher." Broca also introduced a table for recording the fusion of the sutures. Ribbe uses this table, changing only the number value for the order of the fusion (See Fig. 4). In concluding his study Ribbe offers the following information relative to the order of sutural obliterations:
"In the internal table of the skull, synostosis begins at the le%el of the obelion and from there propagates by continuity either forwards or backwards to the asterion or to the sphenoid. The temporal sutures are the first to seal.
"The order of sutural obliteration is as follows: (1) sagittal, (2) coronal, (3) lambdoidal. Occasionally, in the proportion of one time in three, the lambdoid fuses before the coronal. In the external table, synostosis appears generally in the region of the obelion among colored and in a great majority of superior races. The sagittal divisions fuse in the following order: (1 ) obelion, (2) vertex. (3) posterior region. (4) anterior region. The order of fusion of the coronal suture is as follows: ( I ) temporal. (2) bregmatic, (3) complicated division. This order is somewhat confused among Chinamen, Malays and Peruvians. The order of fusion for the lambdoid suture is as follows: ( I ) lambdoic portion, (2) median portion, (3) inferior portion. Near the pterion, the spheno-frontal suture closes before the spheno-parietal suture. The mastoido-parietal suture in nearly all races is one of the last to fuse. Ossification normally appears in the external tables of superior races at about twenty years of age in the youngest and fifty-five at the very latest, averaging between forty and forty-five years of age. In inferior races these fuse between twenty-five and twenty-eight years of age. The progression of fusion of sutures is the same internally and externally, although frequently it is asymmetrical at the levels of the transversal and lateral sutures. It is in general more advanced on the right for the lambdoid, on the left for the coronal and peripterion sutures. The majority of human crania are asymmetrical.
"In young individuals the internal table of the skull shows dentations that disappear with age and fuse into the diploe."
Zanolli, in a study of the obliteration of the cranial sutures, quotes Ribbe, Testut, Tidy and Topinard, but concludes that the ectocranial construction is an insufficient criterion from which to judge the probable age of the individual, stating that the endocranial construction is more important. Zanolli further infers that the order of sutural occlusion is neither regular nor constant; that it is apparently more precocious in the male, where it becomes manifest mostly at about twenty-five years, than in the female, where it is delayed to about thirty years; and that sutural obliteration appears to be more regular and orderly in the female than in the male.
Dwight, in the study of one hundred observations, which study is, however, culled from an assortment of skulls so mixed with regard to sex and race as partly to vitiate any absolute inferences, arrived at the conclusion that the sutures begin to close at a much earlier age than had ever before been stated; that the closing almost invariably begins endocranially, although the process does not at all necessarily appear first on the outside opposite the points previously fusing on the inside; and that the time of closure of any particular part of a suture, and the order in which the process advances, are very uncertain. Dwight then offers his opinion as to the usual order for the closure of sutures, as follows:
"I think that closure generally begins in the back part of the sagittal and often as soon or nearly as soon in the lower ends of the coronals. I think that when the sutures close early the coronal usually closes before the lambdoidal, but that in old skulls, on the outside, at least, the lambdoidal is more frequently obliterated than the coronal. On the inside of old skulls there is very often a minute line showing the position of the apex of the lambdoidal suture when all the others are quite gone. A persistent frontal suture is one of the last to disappear, as has been previously taught.
"As to the rules for determining the age of the skull from the condition of the sutures, it is necessary only to compare them with the observations recorded in this table to see what they are worth. It must not be forgotten that there are other guides to the age of the skull; and I am not prepared to assert that, taken together with them, the sutures are absolutely worthless in the hands of an experienced anatomist. I am sure that to anyone else the rules in question are misleading and dangerous."
Parsons and Box, in a detailed study completed in 1905, corroborate the conclusions arrived at fifteen years before by Dwight, that the closure of sutures may occur in a healthy skull before thirty, though it is rare, and, for practical purposes, the absence of any internal obliteration should fix the probable age at less than thirty. Parsons and Box further add that:
"Over thirty there is always a fair amount of obliteration of the coronal and sagittal sutures internally, while over fifty usually, and over sixty always, all the entocranial sutures are obliterated.
"The ectocranial sutures are so variable that no estimate of age should be made from them when the inside of the skull can be looked at, and the fact that so few museum skulls are opened detracts very much from the practical value of many of our great collections.
"With regard to the place at which ossification usually begins, Dwight is doubtful whether it is below the stephanion or at the obelion, though he rather favors the latter place, and other authors seem divided in their opinions. Our own evidence makes us think that somewhere in the lower half of the entocranial aspect of the coronal suture obliteration usually commences, and that this is followed very rapidly by external obliteration of the same suture below the stephanioit where the temporal ridge crosses it.
"The sagittal suture seems to close internally about the region of the obelion, and soon after wards at its anterior part. the posterior inch sometimes remaining patent after all the rest is obliterated. There can be no doubt that the accepted statement that the suture first closes externally at its simplest part, that is, at the obelion, is correct, though this is subsequent to the internal appearance of obliteration, and is often delayed till old age is reached. Picozzo says that in the male the obelion first closes, and in the female the middle of the sagittal suture, but if he is referring to the outside of the skull all our evidence goes against this statement as far as females are concerned.
"The lambdoid suture closes later than the coronal and sagittal as a rule; this we are not surprised to find, when we remember its markedly serrated appearance. As far as the three sutures with which we have alrady dealt are concerned, the rule seems to be that the simpler the suture the earlier its closure, and this holds good with the spheno-parietal and spheno-frontal sutures, which are always closed when closure has occurred beneath the stephanion, though it does not apply to the squamous suture, which closes very late, if at all. Taking the ento-cranial closure of the lambdoid, we find that, out of twentysix skulls below forty, it is only closed in five. After forty closure is more usual, and a careful review of our records makes us believe that obliteration generally begins midway between the lambda and the occipito-mastoid articulation, and that the upper part near the lambda closes last. On the outside of the skull the closure of the suture is later, and the upper part is often the earliest to close, thus bearing out Dwight's contention that the ecto and entocranial points of obliteration do not necessarily correspond. We have no evidence, on the other hand, that Dwight's statement, that, when the sutures close late, the lambdoid is usually in advance of the coronal ectocranially, is correct.
"In our eighty-two skulls six showed signs of a metopic suture, and the evidence of this small number shows that, as in other sutures, entocranial precedes ectocranial closure. Apparently internal obliteration begins at the lower part. It is sometimes taught, though we are unable to trace the statement to its source, that when the metopic suture fails to close at its usual time it is the last of all to be obliterated. Our records, as far as they go, do not induce us to place much reliance on this.
"With regard to the side on which closure first begins, Sauvage ("Sur 1'etat senile du Crane," Bulletin de la Soc. d' Anihropologie, Paris, 1870) says that both in the coronal and lambdoid sutures the right closes before the left. In our records there are only two in which the obliteration has been caught in a unilateral condition, and in both these it is the left side on which it is commencing. We are in agreement with Picozzo that male skulls are obliterated somewhat earlier than female."
For purposes of roentgen ray anthropology the serration as it manifests on the roentgenogram may be reported as: None-flight-Medium-Complex.
If it is thought desirable, the standards proposed by Broca or advocated by Ribbe and others, may be used; and the qualitative descriptions above enumerated are quite sufficient if they are applied with diligent care. Only the middle portion of the coronal suture and the middle portion of the lambdoidal suture are of significant interest to the roentgenologist. In normal skulls when the middle portion of the coronal suture is at all visualized with any of its serrations in the male skull the age of the subject is less than thirty; in the female less than thirty-five; and for the middle portion of the lambdoidal suture, its visibility indicates in the male fifty or less years, and in the female fifty-five to sixty years. These values are based on relatively few observations and can not be considered entirely accurate; nor is it advisable that unusual care be exercised in inferring the age from the state of fusion of the various sutures by reason of the great difficulty confidently to exclude the effect of pathology on these structures.

SUTURE SYNOSTOSIS

Premature synostosis of the sutures is meant to convey that the fissures of the skull ossify before their usual or normal time. The synostosis of certain sutures may be present at the time of birth, or may set in during the first months after birth; but usually it makes its appearance at a much later period. The cause of premature synostosis is not definitely known. It is assumed that the most usual cause is a constitutional skeletal disease, particularly rachitis. Premature synostosis has been referred to as a racial peculiarity ; and the conjecture has been advanced that synostosis may result from the pressure of bones that bear against each other in the fetus during uterine confinement or at the time of labor. That uterine confinement and labor may have some influence on the subsequent shape of the skull is in part subscribed to by the findings of Mueller, who teaches that the obstetrical presentation of the child at birth casts its influence on the newborn head so that the shape remains thereafter permanently moulded according to the type of presentation. Gross irregularities produced by premature synostosis appear as a result of the fact that the skull is unable to increase in size in the direction perpendicular to the plane of the obliterated suture. Cranial deformations that arise as the result of premature synostosis have been classed by Virchow, quoted by Topinard, as follows:

1. Dolichocephaly.
(a) Median-superior synostosis; simple dolichocephaly through synostosis of the sagittal ; varied or sphenocephaly, in which there is a compensatory development in the bregmatic region.
(b) Synostosis of the lateralinferior including leptocephaly by fusion of the frontal and sphenoidal, and klinocephaly by fusion of the parietal and sphenoidal or temporal.

2. Brachycephaly.
(a) Posterior synostosis, comprising pachycephaly by fusion of the parietal and occipital, and oxycephaly by fusion of the parietal and occipital or temporal and compensatory development in the region of the bregma.
(b) Antero-posterior and lateral synostosis, comprising platycephaly by fusion of the lateral, frontal and parietal ; trochocephaly, by fusion of the parietal and a part of the frontal; plagocephaly, by fusion unilaterally of the parietal and frontal.
(c) Median-inferior synostosis: Simple brachycephaly by precociou's~ fusion of the sphenoidal basilary suture.

Lucae has also proposed a classification introducing new terms for every eccentric shape according to the following selfexplanatory denominations:

As Stocking so well says:
"There seems to be some confusion in the terminology used for the various shapes of heads. This is perhaps due chiefly to two causes, the first one of which is undoubtedly the fact that anthropologic interest seems to have been the most common reason for research and classification up to the present. Whereas it appears to us as being more important to physicians that what there is of clinical significance attached to the different shapes of skulls, both as to etiology and symptoms, should be the feature kept uppermost in mind.
"The second cause for confusion seems to be that too many minor details have crept into the differentiation, and the gross general distinctions have been more or less lost sight of amid the plethora of technical terms.
"It is not difficult to illustrate the confusion of terms in the various classifications by referring to the literature. In German works on the subject 'Turmschaedel' has been generally used to describe a particular kind of head, for which authors in other languages have used terms less descriptive. 'Oxycephalus' is one of them. This word means a pointed head, which is by no means the commonest type of Turmschaedel. Others have used the word 'acrocephalus,' the first portion of which is derived from the Greek word `akron,' meaning top or extremity, and which we make use of in the word `acromegaly' in reference to enlargement of the distal portion of the body. Still others have used the term 'hyperbrachycephalus,' which yet does not describe the condition as acceptably as the word 'turmschaedel'."
From these considerations it appears that pathological deformations of the vault may be classed into three general groups, as suggested by Hrdlicka: (1 ) Scaphocephaly, where the vault is abnormally prolonged and the sagittal suture more or less resembles the keel of a boat. This deformity, which may be accompanied by an annular retrocraniál depression, is due to the premature occlusion of the sagittal suture, and is particularly common among American negroes; (2) acrocephaly, or abnormal increase in the height of the fore part of the vault, due in the main to premature occlusion of parts of the coronal suture; ( 3 ) plagio-cephaly, or asymmetry of the vault produced mostly by premature occlusion of the coronal or lambdoidal suture on one side.
Scaphocephaly, said Minchin and Baer, results by reason of the existence of a single center of ossification for the two parietals; and, said Morselli, because of two points of parietal ossification. But Welcker completely overthrew these erroneous theories. Two tyt)es of scaphocephaly may usually be distinguished and are called by Topinard ordinary and annular. In ordi, nary scaphocephaly the median sagittal suture is lengthened and there is usually a ridge-like bulging of its entire course. Ordinary scaphocephaly may be dominantly frontal, occipital or parietal. Annular scapheocephaly is distinguished by a circular depression found immediately posterior to the coronal suture and giving the skull the appearance, when sagitally viewed, of being composed of two lobes, one anterior and the other posterior.
Acrocephaly may also occur in two distinguishable types. In the first type the skull is raised and resembles a round crown or turret (the turricephaly or turret head of Stocking). In the second type the vault presents the appearance of a rounded bowl.
Acrocephaly is a characteristic of such peculiarity as to attract immediate attention, and may be noted in the living in those individuals of exceptionally high forehead.
Plagiocephaly may result from various causes: (1) A congenital inequality in the two halves of the cranium incident to an inequality in the cerebral hemispheres; (2) the arrested development of a particular cranial segment, as one of the cranial bones; (3) induced flattening, either intentional or as the result of infantile posture in children, as studied especially by Walclier; (4) chronic torticollis; (5) hereditary ethnical deformation derked from exaggerated plagiocephalic parent (Topward) ; (6) synostosis of the coronal or lamboidal sutures. The most common cause of plagiocephaly following premature synostosis is that due to the fusion of the coronal suture either of one of its halves or in its entirety. Fusion of the lambdoidal suture is a less common cause of plagioceplraly.
Besides scaphocephaly, acrocephaly and plagiocephaly, Topinard would include trigonocephaly, described by Welcker and Virchow as due to the congenital synostosis of the mediofrontal suture. \liewed from above, the head presents a generally triangular shape, with the apex at the forehead. In addition to these pathological deformations the nonintentional and intentional artificial deformation may be met in dealing with primitive peoples, Hrdlicka summarizes a description these variations as follows:
"Intentional artificial deformations, which are particularly common in certain parts of this continent and among certain Pacific Islanders, are designed shapings of the head of the new-born infant, as a result of an habitual or religious observance. They are produced by the continued application of direct pressure, by board and pad, bandage and pads, or by a bandage alone, to the bead of the new-born. They are of three main classes, namely, frontooccipital (fiat-head), circumferential ('macrocephalous' or 'Aymara'), and occipital.
"The 'flat-heads' are characterized by a greater or lesser fattening of the front, a corresponding flattening of the occiput, a compensatory bulging of the parietal regions, a more or less marked depression along and just posterior to the coronal suture, and occasionally a more or less marked depression along the posterior portions of the sagittal suture. When pronounced, the last named condition gives rise to the so-called bilobed crania.
"The 'Aymara' deformations are characterized by a more or less marked, broad, circular flattening or depression passing over the frontal bone, the temporal squammae and the lower parts of the parietals, and over the lower portion of the occipital, while the posterior and superior portion of the parietals and the upper part of the occipital protrude in a compensatory way upward and backward. Anterior to the coronal suture in these cases there is generally an elevation, while posterior to the suture we find a more or less pronounced annular depression.
"The occipital deformations resemble those produced accidentally, but in general are more marked. They may represent merely a favored and perhaps assisted incidental flattening due to the resistant head cushion, as among the Navahos and Pueblos; or they may occur, due to less effective methods, as by-products of the flat-head deformation with help of bandages, as among the old Peruvians. These deformations generally involve parts of the parietals, and may be median or lateral. They result in shortening, elevation and broadening of the vault, and in making the fore of head both higher and more vertical."
The pathologic deformations de scribed have as a basis anomalies in the bony metabolism of the cranial skeleton. In addition, certain deformations may arise as the result of encephalic changes, more particularly hydrocephaly and the changes incident to microcephaly.

SIZE OF SKULL

To begin with, the size of the skull is greatly dependent upon the size of the brain; although the cranial skeleton and its contents may be developed, to a certain extent at least, independently (Gratiolet reported the case of an infant in whom the cranium presented a normal conformation; but the brain was, nevertheless, almost entirely un developed and wanting). When, in the skull, there accumulates an undue
amount of fluid, as in hydrocephaly, in crease in the pressure bulges the cranium so as to augment its size; and the distribution in the lines of force of the pressure is such as to be exerted from the resistant bony base against the resillient membranous vault. If the fluid accumulates during intrauterine existence, or shortly after birth, the relatively great plasticity of the membranous vault bulges equally and radially from the bony base. It is in these cases that the median sagittal curve of the vault traced from the nasion to the inion presents a nearly perfect hemispherical projection. If the fluid accumulation begins after the membranous vault has begun to ossify, and has lost much of its initial plasticity, the pressure exerted by
the increasing fluid will be spent against the parts that offer relatively minimum resistance; and since, in the infant, the anterior fontanelles and frontal region in general remain more plastic for a longer period than the posterior cranial sector, acquired hydrocephalus mani fests as a bulging more prominent in
the frontal than in any other region.
It will be found that in general the majority of abnormally large skulls are hydrocephalic. Virchow suggested a two-fold nomenclature for enlarged skulls, calling increases in size due to enlarged brain cephalonic, and increases due to the accumulation of abnormal quantities of cerebrospinal fluid,
hydrocephalic. He further subdivided cephalonic skulls into normal and pathologic, in which the normal show a cranial base that is proportionate to the cranial vault, and the pathologic show a vault that has increased proportion ately more than the base. From the roentgenogram it is sometimes possible
to differentiate between hydrocephalus and cephalonia ; and this differentiation accomplished, the distinction be tween normal and pathological cephalonia can be made by tile roentgen ray rnthropometric study of the proportion that exists between tile base and the rr-ult (Anton and I;hrich have discussed the occurrence of cerebral hypertrophy leading to cephalonia as being in sorr:e cases a congenital affection frequently associated with aplasia of the - uprarenals and with persistence of the thymus).
Hydrocephalus may be congenital or acquired. In addition to the strikingly characteristic enlargement and deferirztion of the skull that accompanies botri congenital and acquired hydrocephalus, there are changes in the orbital rools and also in the sella turcica, in which the latter, by pressure of the accumulating fluid, is in some instances flatte and  widened. It seems that the facial cranium suffers little or no affection in hydrocephalic changes; so that tile cranio-farcial index, subsequently to be described, affords a means of inferring, frorn the roentgenogram, the probability of cranial deformation incident to hydrocephaly.
In contradistinction to hydrocephaly the abnormally small head may be soon recognized as microcephaly.

MICROCEPHALY

Microcephaly is found in two types of subjects. In the first, the intelligence of the individual is conserved, but in the second, it is associated with idiocy or imbecility. It consists of a reduction in the volume of the cerebral mass, or of portions of the encephalon, more especially the posterior or anterior parts. In hydrocephaly the skull is characterized by relative preponderance of the vault as compared to the lack of prominence of the face; but microcephaly manifests in the reverse order. by a full and markedly conspicuous face and a diminutive vault. According to the cranial capacity Broca distinguished two grades of microcephaly which he called, respectively, true microcephaly and demi-microcephaly.
True microcephaly of Broca was associated with the smallest heads, holding a capacity of about five hundred cubic centimeters, and demi-microcephaly was intermediate between true microcephaly and normal capacity, or about one thousand cubic centimeters. True microcephaly is instantly recognized, though it is relatively uncommon. Demimicrocephaly may be so slight as to require the measure of the diameters of the skull for its appreciation; and on this point roentgen ray anthropomelry affords in the living what could never before be obtained, a measure of the internal diameters of the skull. All methods for the calculation of cranial cubic contents in the living have been based on the use of the various diameters or of the cranial module without other than an estimate of the thickness of the component bones. A roentgenographic means for estimating cranial capacity will shortly be discussed in the section on measurements.