206 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxn. 



The absolute and relative length proportions of the cerebellar fossae, 

 contrasted between adults and young, man and animals, sexes, races, 

 and in the main cranial forms, are as follows: 



Length proportions of postero-inferlor fossx in relation to greatest external and mean 

 internal length of the skull. 



Subjects. 



Num- 

 ber of 



skulls. 



Adults: 



Whites, males — 



Dolichoeephals 



Mesocephals 



Brachycephals 



Whites, females— 



Dolichoeephals 



Mesocephals 



Brachycephals 



Indians, males — 



Dolichoeephals 



Brachycephals 



Negroes: 



Males, dolicho- and mesocephals 

 Females, dolicho- and mesocephals 

 White fetuses and children, brachy 



cephals 



Colored fetu.ses and children: 



Brachycephals , 



Dolicho- and mesocephals 



Anthropoid apes: 



Chimpanzees 



Orangs 



Gibbons 



Monkeys and lemurs: 



Maraeii.t pelups 



Cc '"'■'•■ liijiiiih iicu.s 



AUiiiiitii XI tiiciila 



Midas 



Lemur varius 



Average 



external 



maximum 



length of 



skull. 



Average 



mean 

 length of 

 the 2 pos- 



tero-in'e- 

 rior " 



19.4 



18.7 

 18.2 



17.8 

 17.8 

 17.3 



18.3 

 16.9 



18.6 

 17.7 



11.9 



11.9 



7.5 



8.2 

 7.5 

 7.0 

 4.1 

 6.0 



mm. 

 63.4 

 63. 7 

 62.9 



58.6 

 61.1 

 60.4 



63.6 

 59. 2 



63.9 

 60.3 



32.2 

 32.2 



42.8 

 41.2 

 24.6 



24.0 

 18.7 

 20.5 

 11.5 

 16.0 



Average 

 relation of 

 the length 

 of the fos- 

 sae to the 



dorsal 

 length of 

 the skull. 



33.0 

 34.0 

 34.4 



32.9 

 34.4 

 35.0 



34.8 

 34.9 



34.4 

 34.1 



36.0 



3:.o 



33.3 



36.0 

 34.5 

 32.6 



29. 2 

 25.0 

 29.3 

 28.0 

 26.7 



Average 

 relation of 

 the length \^^^^. 



of the fos- 

 S8e to the 

 ven tral 

 length of 

 the skull. 



ber of 

 skulls. 



35.7 

 36.4 

 37.5 



35.6 

 37.0 

 38.2 



38.2 

 38.5 



37.9 

 37.1 



36.4 

 35.1 



38.8 

 39.1 

 33.8 



31.2 

 28.0 

 34.9 

 29.3 

 30.2 



The average relative proportions of the cerebellar fossae differ, it 

 is seen, but little between human adult.s and human young, both 

 groups taken as a whole. If the cases are taken individually, it is 

 found that there is a greater variation in the relative proportions of 

 the cavities in the fetuses and young than in the adults (young, 

 27.2-47.2; adults, 28.8-40.1; in the young, proportions below 30 in 9 

 per cent and above 40 in 5.1 per cent of the foss», in adults, those 

 below 30 in 1.5, those above 40 in 0.4 per cent of the cavities). These 

 greater inequalities in the young are in all probability due more to 

 the relatively abundant tissues about and especially in the rear of the 

 cerebellum than to variation in the hind-brain itself. The volume 

 itself of the fetal cerebellar fosste would be smaller were these tissues 

 not present, and their relative length would not equal that in the adults. 

 Among anthropoid apes the relative dimensions of the cerebellar 

 fossae in the chimpanzee and orang are much like those in some of the 

 series of human adults, but these in the gibbon are noticeably lower, 

 and they are still lower, with one exception, in the nionke3^s and lemur. 



