on Fossil Quadrumana. 



501 



The principal dimensions are as follow : — 



Dimensions. Sewalik Fossil Monkey. Semnopithecus Entellut. 



Extreme length of astragalus 1-3 inch 1-35 inch. 



Extreme width of body of astragalus 1 • 



liergth of body ... . . . , 



. . . 0'8 





. .. 0-65 



Thickness of ditto 



0-45 



FossO (1). Recent (2). 



I 



1-03 

 0-8.5 

 0-65 

 0-5 



Fossil (3). 



Recent (4). 



The chief peculiarities of the fossil astragalus^ compared with that of the 

 Entellus, are these : — The upper articulating surface for the tibia (a) is more 

 convex than in the Entellus, and less square in the outline^ the lateral margins 

 (a, b) approximating as they run backwards ; the outer one being also more 

 elevated. The peroneal articulation (b) is precisely of the same form and 

 extent as in the Entellus ; and the rough fossa between it and the large cal- 

 canean surface (d) also corresponds. The articular surface (c) for the inner 

 malleolus somewhat differs : in the fossil it is long, shallow, and rather 

 pyriform in outline, while in the Entellus it is cup-shaped, deeper, and more 

 extensive. The'other pits and inequalities of the inner side correspond ; but 

 the entire surface slopes off more obliquely in the fossil. The great calca- 

 nean surface (d) has the same diagonal direction, with reference to the upper 

 surface, as in the Entellus : it has also the same form, but it is more vaulted, 

 and has less stretch and width. Its inner margin is bounded by the shallow, 

 pulley-shaped fossa (e) for the tendon of the Jlexor poUicis longus muscle, en- 

 tirely as in the Entellus ; and the rough pit between it and the anterior cal- 

 canean surface (f) is alike in both. The head-and-neck apophysis is sent off 

 afe in the Entellus. The upper surface of the neck (g) is narrower and less 

 sloped. The scaphoid surface of the head (h) is altogether less extensive. 

 The head itself is not so thick and massive, and its long direction slopes more 

 obliquely upwards than in the Entellus ; its inferior articular surface is less, 

 and there is a wide, rectagonal, rough gutter or fossa (x) running half way 

 across, so as to make two surfaces. In the Entellus the fossa is obsolete, and 



3t2 



