312 MR. -w. L. H. DUCKWOETH O'S [Mar. 7> 



In 9 adult female Chimpanzees, on the otlier hand, in only one had 

 the temporal ridges united to form a slight crest : the average 

 distance between them is 22 mm. These ridges in the male 

 Gorilla reach the sagittal suture as the canine teeth cut and fuse 

 into a ridge, which continues to grow all through life. In the male 

 Chimpanzee they only occasionally unite to form a ridge. The 

 develdpment of the temporal ridges, the height to which they reach 

 on the roof of the skull, depends on tlie dentition. The condition 

 in the adult female Chimpanzee corresponds to the stage of develop- 

 ment found in a male Gorilla cutting its second molar tooth. 



The lower jaw in the female Gorilla, almost without exceptiou, 

 exceeds in every dimension that of the female Chimpanzee. 



11. Summary. 



The Gorilla may be distinguished in life from the Chimpanzee 

 by its sullen, untamable, ferocious nature ; its long nasal bones 

 descending far below the level of the infra-orbital margin ; its 

 great alar nasal folds running to the margin of the upper lip ; its 

 great peculiar molar, premolar, and canine teeth; its broad, 

 short, thick webbed hands and feet ; its long heel and the great 

 length of its upper arm with the smaller development of the 

 forearm. 



EXPLANATION OP PLATE XX. 



Anthropopifhecus troglodytes kooloo-kaniba. Taken from the specimen named 

 "Johanna," living in tlie collection of Messrs. Barnum and Bailey. 



2. Further Note on Specific DifFerences in the Anthropoid 

 Apes. By W. L. H. Duckworth, M.A., Fellow of Jesus 

 College, Cambridge. 



[Receiyed March 4, 1899.] 



1. After reading a note on this subject to this Society in 

 December 1898, I learned that in the Zoological Museum at 

 Jena is an Ape, the determination of whose species has given rise 

 to some discussion : the point in dispute being, whether it should 

 be described as a Gorilla or a Chimpanzee. Through the kindness 

 of Professor Haeckel I have been enabled to examine the specimen 

 and have arrived at the following conclusion — that, although 

 labelled " Junger weiblicher Gorilla," ^ neither the stuffed skin nor 

 the skeleton afford any evidence to justify the term Gorilla ; and 

 the facts that hardly a suture remains unclosed in the skull, that 

 every epiphysis has long been fused with its diaphysis in the limb- 

 bones, and that the teeth are much worn down, indicate that this 

 was an ayed, and not a young female. The average transverse 

 diameter of the crowns of the molar teeth is 9-7 mm. (c/. the ape 

 " A"' at Cambridge, where the average is 10'4; and an undoubted 

 female Gorilla with 1-i mm.) ; and the mounted skeleton measures 



^ The label runs : — " Troglodytes gorilla (Cuv.). Junger weiblicher Gorilla, 

 von einem L^runga Neger, 1885, in der Kolonie Gaboon erlegt." 



