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KNOWLEDGE 



[July '2, 1894. 



That these apes are our nearest cousins is probably 

 well known to all our readers : but the degree and extent 

 of this relationship, as well as the characters by which it 

 is displayed, are probably far less familiar to many of 

 them. In the first place it will be noticed 

 that we speak of this relationship as one of 

 cousinship, and not of ancestry ; and it is well 

 that the reader should at once free himself 

 from any idea that there is any vestige of 

 direct ancestral kinship between these, for the 

 most part, hideous creatures and himself. 

 Such relationship as does exist — and we cannot 

 but believe that such there is— is of a compara- 

 tively distant kind ; and the common ancestor 

 must have lived ages before the mammoth 

 roamed over the plains and valleys of England, 

 since at that date man was as distinctly differ- 

 entiated from the apes as he is in the present 

 century. Whether this " missing link '' will 

 ever turn up, or in what country it is most 

 likely to have lived, are questions impossible to 

 answer ; but from the extreme rarity with 

 which fossil remains of man-like apes are found 

 in countries where they are known to have 

 existed for long ages, and from the probability 

 that the disti-ibutional area of the aforesaid 

 " link " was extremely limited, we cannot give 

 much hope that the researches of palwontolo- 

 gists will ever be rewarded by such a " find." 



From their large bodily size, coupled with 

 that terrible caricature of the human face 

 and form characterizing the more typical re- 

 presentatives of the man-like apes, no one 

 would have any difficulty in picking out these 

 creatures from among their lower relatives. 

 There might, however, be some hesitation with 

 regard to the long-armed gibbons, a specimen 

 of which is represented in our third full page 

 illustration ; and we, therefore, proceed at 

 once to point out how the members of the 

 man-like group may be distinguished as a 

 whole from other monkeys. 



We presume, in the first place, that all 

 our readers are aware that apes, monkeys, and 

 lemurs constitute one great mammalian order 

 — the Primates ; and likewise that lemurs differ 

 from apes and monkeys by their long fox-like faces and 

 immobile expression, to say nothing of many anatomical 

 peculiarities into the consideration of which it will be 

 unnecessary to enter on this occasion. Possibly we shall 

 be presuming too much as to the extent of their zoological 

 knowledge if we also assume that they are acquainted with 

 the difference between the apes and monkeys of the Old 

 World and the monkeys of the New ; and it is accordingly 

 advisable to make this clear at starting. The whole 

 of the Old World representatives of the division of the 

 order to which we are confining our attention are 

 characterized by having teeth agreeing both in number 

 and aiTangement with those of man. Thus in all cases 

 in each jaw there are two pairs of incisors, a single pair of 

 eye-teeth, tusks, or canines, and five pairs of cheek-teeth, 

 of which the last, or " wisdom-tooth," is frequently very 

 late in making its appearance, as shown in the accompany- 

 ing figure of the lower jaw of an immature chimpanzee, in 

 which it is still imbedded in a cavity in the bone, the top 

 of which is open. It is further essential to observe that 

 of these five cheek-teeth the first two on each side are 

 simpler than the three hinder ones, and are preceded in the 

 infant by milk-teeth, whereas the latter have no such 



predecessors. It is accordingly the custom to call 

 the two simpler teeth premolars or bicuspids, and the 

 three more complex ones molars. If now, we examine an 

 ordinary American monkey, we shall find six cheek-teeth 



Lowoi- jaw of au immature Chimpanzee, with the "wisdom-tooth" still concealed 



in its socket. 



on each side of both the upper and lower jaws, of which 

 half are premolars and half molars, while in the marmosets, 

 which constitute a second American family, although the 

 total number of cheek-teeth is the same as in the Old 

 World forms, yet the proportion is different, there being 

 three premolars and two molars. It may, therefore, be 

 concisely stated that all American monkeys differ from 

 their Old World cousins in having three instead of two pairs 

 of premolar teeth, whence it may be inferred that they 

 belong to a lower and more generalized type, there being a 

 universal tendency throughout the higher vertebrates to a 

 diminution, or disappearance of the teeth with the advance 

 of specialization. In the marmosets the loss of the last 

 molar is unique in the higher division of the order, and is 

 indeed a somewhat remarkable peculiarity to occur in a 

 herbivorous mammal, among which the reduction is usually 

 confined to the front and premolar teeth. 



As the teeth serve most readily to differentiate the 

 Old World monkeys from their American allies, so the 

 man-like apes are sharply distinguished from their relatives 

 by the conformation of these organs. As shown in the 

 accompanying figure of the lower jaw of the chimpanzee, 

 the molar teeth of the man-like apes closely resemble our 



