260 THE MANUS. [CHAP. 



rally of a more elongated form, and more salient than in 

 Man ; and there is usually a small rounded radial sesamoid 

 (rs) articulating moveably to the border of the scaphoid 

 and trapezium, and connected with the tendon of the flexor 

 carpi radialis. 



In the Potto (Perodicticus) there is an additional bone in 

 the palmar side of the carpus, an ossification in the ligament 

 connecting the palmar processes of the trapezium and 

 unciform bones, and forming with these processes a com- 

 plete bony ring, through which the flexor tendons pass. 1 



FlG. 87. — Bones of the carpus of a Baboon (Cynocephalus anttlvs). \. s scaphoid ; 

 I lunar ; c cuneiform ; / pisiform ; ce central ; rs radial sesamoid ; tin trapezium ; 

 td trapezoid; m magnum ; u unciform; 1 — v the metacarpals. 



The metacarpals and phalanges are of the complete and 

 normal number in all, with the following exceptions. In the 

 African genus of Long-tailed Monkeys (Colobus), and also in 

 the American Spider Monkeys (A teles), the thumb is rudi- 

 mentary, having usually but one very minute phalanx, in 

 addition to the metacarpal. In the Potto {Perodicticus) and 

 some allied Lemurince, the second (or index) digit is very 

 much shorter than the others, and has but two rudimentary 

 phalanges. 



The phalanges are generally more curved than in Man, 



1 Mivart, "On the Appendicular Skeleton of the Primates;" Phil. 

 Trans. 1867. 



