198 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. XXXII. 



The relation to the dorsal length of the skull is in these cases proba- 

 bh" the more reliable, as the ventral length can easil}^ and impercepti- 

 bly be augmented a little by the relaxation of the bones consequent 

 upon the removal of the parietals, which constituted the method of 

 opening the small skulls. However, compared to either the external 

 or internal cranial length, the fosste are in the majority of the cases 

 shown to be smaller than during later development. In fetuses in 

 which the vertex-breech length is above 20 cm. the relative dimen- 

 sions of the fossffi are much more like those in adults, showing that 

 the attainment of their full relative length takes place very early. 



In anthropoid apes, monkeys, and lemur, with the sole exception of 

 the orang, the postero-superior cavities are relatively shorter than in 

 human adults, agreeing in this respect with what exists in the earlier 

 stages of fetal life in man. The proportions are particularly low in 

 the lemur. 



No definite difference in the relative length of the postero-superior 

 cavities appears in the sexes. Among races, they are longest in the 

 Indian, the whites and negroes being near alike. As to the main 

 cranial forms, among whites the fossae are in both sexes in the average 

 slightly longer in the meso- than in the dolichocephals, and stilllonger 

 in the brachycephals, while among the Indians and the young it is the 

 fossffi in the dolichocephals that are slightly longer. The differences 

 in this respect are, however, throughout too small to be of nmch sig- 

 nificance; besides, individual exceptions are numerous in all the series. 



THE THREE CEREBRAL FOSSiE CONSIDERED TOGETHER. 



The sum of the lengths of the three cerebral f ossse on each side shows 

 this interesting distribution: 



Sum of lengUis of cerebral fossse. 



Subjects. 



No. of 

 cases. 



a+m+ps. 



Right 

 side. 



Left 

 side. 



Whites, males: 



Dolichoceplials 



Mesocephals 



Brachycephals 



Whites, females: 



I)( iliolif)C('phals 



Mesocejihiils 



Brachycephals 



Indians, males: 



Dolichocephals 



Brachycephals 



Negroes, males: 



Dolicho- and mesocephals 

 Negroes, females: 



Dolicho- and mesocephals 



Human fetuses and young 



Anthropoid apes 



Monkeys and lemur 



cm. 

 18.9 

 18.7 

 18.1 



17.4 

 17.9 

 17.6 



17.9 

 17.3 



18.2 



17.5 

 9.55 



11.3 

 6.9 



19.0 



18.8 

 18.4 



17.6 

 18.0 

 17.5 



18.1 



17.1 



18.4 



17.5 

 9.5 



11.3 

 6.9 



[o, anterior; vi, middle; ps, postero-superior fossa.] 



