312 MR. w. L. H. DUCKWOETH OX [Mar. 7) 



In 9 adult female Chimpanzees, on the other 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 

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

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

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

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



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

 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 OF PLATE XX. 



Anthropopithecus troglodytes Tcooloo-kamha. Taken from the specimen named 

 "Johanna," living in the 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. 



[Eeceived 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. Tiirough 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 stulfed 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 aged, and not a young female. The average transverse 

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

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

 female Gorilla with 14 mm.) ; and the mounted skeleton measures 



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

 Ton einem Urunga Neger, 1885, in der Kolonie Gaboon erlegt." 



