THE GREAT CHIMPANZEE. 417 



of the crowns of the molars and premolars, appear likewise from the actual results of 

 observation to be equally predetermined and non-modifiabic characters. 



No known cause of change productive of varieties of mammalian species could operate 

 in altering the size, the shape and the connections of the premaxillary bones, which so 

 remarkably distinguish the great Troglodijles Gorilla, not from Man only, but from all 

 other anthropoid apes. We know as little the conditions which protract the period of 

 the obliteration of the sutures of the premaxillary bones in the Tr. Gorilla beyond the 

 period at which they disappear in the Tr. niger, as we do those that cause them to dis- 

 appear in Man earlier than they do even in the smaller species of Chimpanzee. 



There is not, in fact, any other character than those founded upon the developments 

 of bone for the attachment of muscles, which is known to be subject to change through 

 the operation of external causes : nine-tenths therefore of the diflerences which are cited 

 in the summary at p. 413, as distinguishing the great Chimpanzee from the human 

 species, must stand in contravention of the hypothesis of transmutation and progressive 

 development until the supporters of that hypothesis are enabled to adduce the facts 

 and cases which demonstrate the conditions of the modifications of such characters. 



If the consideration of the cranial and dental characters of the Troglodytes Gorilla 

 has led legitimately to the conclusion that it is specifically distinct from the TroglodytcK 

 niger, the hiatus is still greater that divides it from the human species ; between the 

 extremest varieties of which there is no osteological and dental distinction which can 

 be compared to that manifested by the shorter piemaxillaries and larger incisors of the 

 Troglodytes niger as compared with the Trogl. Gorilla. 



The analogy which the establishment of the second and more formidable species of 

 Chimpanzee in Africa has brought to light between the representation of the genus 

 Troglodytes in that continent and that of the genus Pithecus in the great islands of the 

 Indian Archipelago is very close and interesting. As the Troglodytes Gorilla parallels 

 the Pithecus Wurmhii, so the Troglodytes niger parallels the Pithecus Morio, and an 

 unexpected illustration has thus been gained of the soundness of the interpretation of 

 the specific distinction of that smaller and more anthropoid Orang. 



It is not without interest to observe, that as the generic forms of the Quadrumana 

 approach the Bimanous Order, they are represented by fewer species. The Gibbons 

 (Hylohates) scarcely number more than half-a-dozen species ; Pithecus has but two 

 species, or at most three ; Troglodytes is represented by two species. 



The unity of the human species I regard as demonstrated by the constancy of those 

 osteological and dental characters to which my attention has been more particularly 

 directed in the investigation of the corresponding characters in the higher Quadrumana, 

 and the importance of the comparison will justify the minuteness with which they have 

 been detailed. 



Man is the sole species of his Genus, the sole representative of his Order ; he has no 

 nearer physical relations with the brute-kind than those which mark the primary (un- 

 guiculate) division of the placental subclass of Mammalia. 



