542 



CETACEA. 



had noted a few dimintitive muscular slips as alone extant between the scapula and 

 humerus ; the lower bony segments being supposed to be held together solely by 

 aponeuroses, and therefore to be comparatively immobile. Platanista I have found 

 to be another genus, whereia the manus is provided with tendons indicative of true 

 flexor muscles. 



Separate extensor tendons on the dorsal siu'face of the manus are by no means 

 defined or clear. A comparatively aborted extensor communis digitorum muscle 

 appears as a very thin, but broad layer of fleshy fibres which covers the ulna. 

 At the cuneiform and os magnum, partly by their textural characteristics and 

 longitudinal direction, three very thin and very much flattened tendons are observed 

 to diverge and supply the third, fourth and fifth digits respectively, at least as far 

 as their second phalanx. Both the pseudo-belly and tendons of this extensor are 

 very considerably interwoven with the lateral and superincumbent fibrous tissue. 

 The latter, moreover, is fixmly adherent to, and with the greatest difiiculty separated 

 from, the skin itself. 



Fig. 20. 



Fig. 19. 



Fig. 19.— The right forearm of Platanista dissected on its inner surface to show musoulo-tendinous parts as de- 

 scribed in text. I, II, III, IV, V digits respectively ; fid, flexor longus digitorum ; feu, flexor carpi 

 ulnaris ; ecu, extensor carpi ulnaris ; hy, vessels supplying limb. 



Fig. 20.— A view of the foreshortened narrow ulnar margin of limb, where the relations of (/cm ) flexor and (em) 

 extensor carpi uln.iris are brought out. 

 Both figures from a fully adult animal are necessarily greatly reduced. 



A flexor longus digitorum is still better marked, though by no means a promi- 

 nent muscle. A longitudinal flat adpressed band of fleshy fibres a trifle narrower 

 and thicker, is also adherent to the ulna. This becomes highly tendinous as the 



