72 BONES OF THE HEAD. 



between several bones of the skull and vertebrae in man and animals is generally ad- 

 mitted by scientific anatomists, and that the difficulties which oppose the enunciation 

 of clearer views on the serial relations of the cranial elements arise in great measure 

 from deficient information and want of agreement among anatomists as to individual 

 points in the correspondence of those elements throughout the animal series. (See, 

 in addition to the works previously referred to, Huxley, " Elements of Comparative 

 Anatomy," 1864 ; Cleland, " On the Relations of the Vomer," &c., Trans. Hoy. Soc. 

 1862; Spix, " Cephalogenesis," 1815; Von Baer, " Entwickelungsgesch. der Thiere," 

 182837 ; Hallcuan, " Die Vergleich. Anat. des Schlafenbeins," 1837 ; Bojanus in 

 Isis, 18181819.) 



THE VARIOUS FORMS OF THE SKULL. 



I. Differences according to Age. In the earlier stages of its development the posterior 

 part of the skull bears a very large proportion to the anterior part; so much so, that 

 in the second month of foetal life the line of the tentorium cerebelli is vertical to the 

 basis cranii, and divides the cranial cavity almost equally into two parts. At th6 time 

 of birth the parietal region has reached its largest development in proportion to the 

 occipital and frontal regions. The greatest frontal breadth is then smaller in pro- 

 portion to that between the parietal eminences than afterwards. In the first years 

 of childhood the superior parts of the skull grow more rapidly than the base. Thus, 

 in the frontal region, the upper part of the frontal bone grows more rapidly than its 

 orbital processes, giving the prominent appearance of the frontal eminences peculiar 

 to children. The face at birth is calculated as being scarcely an eighth of the bulk 

 of the rest of the head, while in the adult it is at least a half (Froriep, " Characteristik 

 des Kopfes nach dem Entwicklungsgesetz desselben "). In harmony with the growth 

 of the face the lower part of the forehead is brought forward by elongation of the 

 anterior cranial fossa, and on the approach of adult age it becomes in the male still 

 more prominent by the expansion of the frontal sinuses. The face becomes elongated 

 in the progress of growth, partly by increased height of the nasal fossae, partly by 

 the growth of the teeth and the enlargement of the alveolar arches of the jaws. In 

 old age the proportion of the face to the cranium is diminished by the loss of the 

 teeth and absorption of the alveolar portions of the jaws. In consequence of this the 

 upper jaw retreats, while in the lower jaw the same cause gives, especially when the 

 mouth is closed, a greater seeming prominence to the chin. 



II. Sexual Differences. The female skull is, in general, smaller, lighter, and smoother 

 than that of the male ; it is less marked by muscular prominences, and has also the 

 frontal sinus less developed. The face is smaller in proportion to the cranium, the jaws 

 narrower, and the frontal and occipital regions less capacious in proportion to the 

 parietal. (Huschke.) The female skull resembles the formed skull of the boy more 

 than that of the adult male ; but it must also be admitted that it is often impossible 

 to determine the sex by the appearance or form of a skull. 



III. National Differences. That characteristic forms of skull are presented by the 

 various races of men has probably been long known, but was first distinctly pointed 

 out by Camper. Subsequently the investigations of Blumenbach raised the study of 

 those different forms to a recognised position in ethnology. The extent and constancy 

 of the ethnical differences of skulls are matters open to discussion ; but it must be 

 allowed, that although many skulls are to be met with which fail to exhibit the 

 characteristics of the race to which they belong, or which present peculiarities similar 

 to those of nations considerably removed from them, yet not only are there certain 

 forms of skull highly distinctive of the principal varieties of mankind, but the pre- 

 vailing form in one nation is often very distinguishable from those found in nations 

 inhabiting neighbouring countries. Great differences occur with respect to size in 

 the skulls of different nations. Among the smallest skulls may be .mentioned those 

 of the Hindoo and ancient Peruvian ; among the most massive those of the Scandi- 

 navian, the Caffre, and the Maori. Various characters are found belonging to the 

 skulls of rude tribes, which serve to distinguish them from those of civilised nations. 

 Among those characters may be mentioned, a depressed appearance between the 

 middle line of the calvarium and the temporal ridge, both of which stand out promi- 

 nently, making the roof of the skull seem like a house-top ; a greater width of the 

 zygomatic arches, and of the anterior nares ; greater strength of the jaws and teeth, 



