DR. J. jniEIE ON THE FORM AND STRUCTURE OF THE JIANATEB. 161 



above the middle of the shaft of the ulna, and end in long triangular pyramidal fleshy 

 masses inserted broadly into the upper half of the ulnar border of the fifth meta- 

 carpal. At the lower part they are much compressed. They act as powerful flexors 

 and abductors of the manus, and give extraordinary breadth to the wrist. The palmaris 

 enwraps the ulnaris, and is in continuity with the tough superficial fascia of the 

 forearm. 



The interossei are most extraordinarily well developed, contrary to what might 

 be expected in such an immoveable encased manus as is possessed by the Manatee. 

 Not only are they large, but they are also found in a manifestly double layer ; and 

 while true flexores breves, there are also a set of dorsal interossei or extensores 

 bi-eves. After removal of the palmar aponeurosis of the combined sublimis and 

 profundus, they are seen arising by tendon from the wrist, and altogether form a 

 broad, flat, fleshy sheet, which covers the palmar surface of the second, third, fourth, 

 and fifth metacarpals — the small flexor brevis and abductor minimi digiti muscles 

 bounding the ulnar side of the plane. The fibres on the second, thu-d, and fourth 

 digits seem to possess a slight tendency to subdivide or divaricate; but those on the 

 fifth are quite single. It is possible these superior palmar muscles may represent en- 

 larged lumbricales or be an anomalously developed flexor brevis manus. Beneath this 

 another equally thick muscular layer of better-defined and somewhat double interossei 

 exists ; they pass to all the digits, excepting the first, and are shorter than the super- 

 ficial interosseous layer. Part of the fibres between the second and third, third and 

 fourth, and fourth and fifth digits obliquely cross the intermetacarpal spaces, and 

 simulate dorsal interossei. These portions approximate the bones. The dorsal inter- 

 ossei are four, and go to the second, third, fourth, and fifth digits respectively. 



The flexor brevis and abductor minimi digiti are each represented by thin muscular 

 bands which run parallel to each other, arising individually from the cuneiform. The 

 latter partly covers the fifth digital interosseous muscle ; and the former is in close 

 approximation with the insertion of the flexor carpi ulnaris : they are inserted by 

 aponeurosis together, along the ulnar edge of the fifth metacarpal. 



(C) Those of the Hip-Girdle: Pelvic and Generative. — Each pelvic bone is suspended 

 abdominally from the first chevron process or that from the fourth lumbar vertebra, by 

 a strong sheet of glistening membrane, and is held in place fore and aft chiefly by two 

 muscles. The anterior one is the rectus abdominis, already described, which terminates 

 in the anterior V-shaped concavity of the female pelvis — and in the male similarly, 

 excepting the difierence in the bone's shape. The posterior one continues as it were 

 the line backwards from the rectus to the chevron bones behind the anus. This post- 

 pelvic muscle is a long, broad band, throughout fleshy, whose origin, in the female 

 as in the male Manatee, is from the posterior border of the pelvic bone. Thence it 

 trends inwards and backwards, passing outside and then behind the rectum towards 

 the middle line, where it is inserted, or becomes incorporated, with the rearward 



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