100 BUREAU OF AMERICAN ETHNOLOGY [Bn.i.. 33 



able number (enumerated on page !M), and the writer will utili/c 

 occasion to give a brief description, with illustrations, of the more 

 remarkable of these specimens, without attempting to explain the 

 exact Mature and cause of their peculiar feature-. 



The whole subject of exceptionally large supraorbital arches and 

 low foreheads deserves exhaustive anatomical study. A low sloping 

 forehead does not occur or has not yet been observed in the fetus 

 and in infants and is extremely rare in the female sex. The i-aim- is 

 true also of heavy supraorbital ridges. Hence both of these characters 

 must l>e regarded as primarily adult and sexual. Their relation is not 

 constant. Most frequently heavy ridges and low forehead coexist 

 and accentuate each other, but low front can be found, as will be 

 seen in some of the specimens to be described, associated with only 

 moderate ridges, and prominent brows are occasionally observed in 

 skulls with good frontal arching. The ridges themselves offer sev- 

 eral points for study. Ordinarily they form elevations which extend 

 over from one-half to two-thirds of the median part of the supra - 

 orbital space, but in rare cases they extend along the whole supra- 

 orbital border, constituting an uninterrupted arch which may have 

 a significance different from that possessed by the ridges of the more 

 usual character. They are affected in volume by the frontal sinuses. 

 but large ridges may coexist with relatively small sinuses and vice 

 versa, showing that some range of variation is inherent in the bony 

 elevations themselves. The corrugator supercilii muscle attached 

 to the glabella may also have some influence on the development of 

 the parts of the ridges nearest to this attachment. A closer compara- 

 tive anatomical study is necessary in this connection. Heavy supra- 

 orbital arches and sloping forehead are found in the adult male 

 gorilla, but these features are much less apparent in the orang. 

 chimpanzee, or gibbon, where we usually find a fairly well arched 

 front, as well as in most of the lower primates. 



The following descriptions and measurements of individual skulls 

 show that in American crania low forehead and prominent supra- 

 orbital ridges are generally not associated with pathological con- 

 ditions of the skull, or with premature occlusion of any of the 

 sutures; where synostosis was observed, it was plainly senile in 

 character. A number of the skulls show small size and according to 

 the ordinary classification would be ranged as microcephals. but 

 Indian skulls of these dimensions are not rare, and it is impos- 

 sible to say that the small size of the brain of the individual is 

 causally connected with the character of the front of any of the 

 specimens. In two of the cases it will l>e seen that the cranial 

 capacity is very fair for Indians. It is an interesting fact that, 

 with one not very pronounced exception, all the low-front crania 

 in the National Museum collection are dolichocephalic or mesocephalic, 



