84 ANATOMICAL NOTES ON MALAY APES. 



Sometimes in dissections of the human body we find the 

 kidneys united by an isthmus of renal matter, such an arrange- 

 ment being called the horse-shoe kidney. Diag. XXVI shows 

 such a variation in Semnopithecus. In Hylobates (see diag. 

 XXXVII) the thyroid gland has a large isthmus lying in front 

 of the trachea ; in Papio this isthmus is very attenuated ; in 

 Semnopithecus it is non-existent, although sometimes a rudi- 

 mentary one may be met with. The thymus gland some- 

 times exists in adults, and sometimes is absent in infants. 



This is but an introduction to the more superficial variations in 

 the quadrumana. We can never know their correct systematic 

 position, nor the direction of their evolutionary tendency, nor 

 their relations to man and to their brother quadrumana, until 

 these be known. And as the all-pervading tropical jungle 

 is gradually being replaced by a vegetation necessary for the 

 sustenance of increasing humanity, the quadrumana will be 

 replaced by man. The century that will hold the apes in its 

 conservatories of rarities, is not far distant, if coming centuries 

 are at all like the great nineteenth. 



VI. — A few Points in Development. 



(a) — Ear. 



In each species of quadrumana the ear steadily main- 

 tains its characteristics. It attains its full growth long before 

 maturity is reached, and still some of its transformations 

 take place late in adult life. Diags. XXVIII and XXIX are from 

 DARWIN' Swell known illustrations showing the occurrence in the 

 human helix of a slight protuberance probably likely represent- 

 ing the aural tip of the lower animals. In Papio cynomolgus 

 this tip is large and remains unfolded (diag. XXX). In Papio 

 nemestrinus and Semnopithecus albocinereus one can see 

 this tip folding in late in foetal life (diags. XXI and XXXII). 

 In a specimen of Hylobates lav this tip was unfolded (diag. 

 XXXII). The aural edge of the orang is folded to a greater 

 extent than that of man and has no lobe, but on the other 

 hand that of the Sevinopithecus has the lobe and resembles 

 closely the human ear. Man seems to have picked many of 

 his parts in common with several of the quadrumana. The 

 teeth of the Semnopitheci are more human than those of the 

 orang. 



