160 DE. J. MUEIE ON THE FORM AND STEUCTTIRE OF THE MANATEE. 



bridging aponeurosis of the bend of the elbow aheady described in connexion with 

 the insertion of the pectoralis major. The thick humeral rate mirabile partially over- 

 lies the biceps muscle. 



The coraco-bracMalis is absent, or indivisibly united with the first head of the biceps. 



Compared with the other muscular structures of the humerus, the hrachialis anticus 

 is enormously developed, and, as it is entirely fleshy, causes the lower and outer 

 aspect of the upper limb to have unusual breadth. The deltoid embraces it above ; 

 and lower than that the brachialis anticus occupies the outer and anterior surface of 

 the humerus. It moreover covers the anterior outer aspect of the elbow-joint, being 

 inserted muscularly into the upper half of the radius forwardly on its radial side. It 

 is a powerful flexor of the forearm. 



The ijronator radii teres is of fair size ; its origin is by a strong flat tendon from the 

 radial side of the inner condyle ; and, with only a moderate amount of fleshy belly, 

 it is inserted obliquely upon the inner surface of the middle third of the shaft of the 

 radius. Its power of pronation is very limited. 



The flexor carpi radialis is long, narrow, and flat, both in tendons and belly. 

 Origin, the inner condyle to the ulnar side of the pronator teres; its distal tendon 

 commences at the lower end of the radius, and is inserted broadly into the proximal 

 extremities of the indicial and poUicial metacarpals. There is no special groove for its 

 reception on the scaphoid and trapezium. 



T\ie flexor sublimis, profundus, and longus pollicis muscles form a complex mass, 

 whose origin is single and extends from the lower part of the inner condyle down the 

 whole length of the inner flat surface of the shaft of the ulna. The thick fleshy belly,, 

 without possessing any clear separation, is nevertheless divisible, chiefly by tendon, into 

 an upper and a lower layer. The upper layer, by a semidivided expanse of palmar fascia, 

 supplies the second, third, and fourth digits. The fascia or united tendinous mass lies 

 upon and is fixed to the broad interosseous muscles, and it is continued on to the 

 proximal ends of the first phalanges of the second, third, and fourth digits. The 

 aponeurosis is not finely interwoven and smooth on its surface, but is easily torn up 

 into parallel coarse threads. The lower layer of this united muscle is fleshy for a short 

 distance further than the upper layer, and does not become tendinous until reaching 

 the palm, whereas the upper layer is tendinous above the wrist. It is inserted 

 into the third and fourth digits, being closely adherent to the superficial tendinous 

 mass. 



From the slightly bent or oblique position assumed by the fifth metacarpal to the 

 ulna, and the very flat condition of bones of the forearm, the ^ja?»iam longus and 

 flexor carpi ulnaris appear to lie both on the dorsal and palmar surface of the 

 limb. They together project, as it were, and fill the angle whose two sides re- 

 spectively are the bones above mentioned. Origin by a flat tendon from the surface 

 of the inner condyle immediately above the flexor communis. The bellies commence 



