No. 2.] AMPHIUMA MEANS. 387 



pectoralis major, arises from the fibres of the omo-humero- 

 maxillaris posterior to the limb, and extending distalward as a 

 radiate muscle, is inserted in the fascia of the muscles of the 

 arm. Immediately beneath this muscle, which covers the en- 

 tire coracoidal region, is found the supracoracoideus, a radiate 

 muscle arising from the ventral surface of the coracoidal carti- 

 lage and extending to its insertion in the head of the humerus. 

 Its function is that of depressing the fore limb. The slender 

 fascia-like deltoideus arises insensibly from the fibres of the 

 omo-humero-maxillaris, and runs along the anterior side of the 

 arm, being slightly inserted on the distal end of the humerus, 

 but continuing as a flexor carpi radialiis to its final insertion 

 in the carpal cartilages. The coraco-humeralis is a mere branch 

 of the omo-humero-maxillaris, and is strongly inserted in the 

 anterior proximal region of the humerus. It draws the limb 

 cephalad. The flexor digitorum communis is a greatly degen- 

 erated muscle arising from the middle part of the humerus and 

 extending downwards to the carpal region. The dorsal aspect 

 of the fore limb presents four muscles very closely bound to- 

 gether by dense fascia. A slender muscle representing the 

 triceps brachii arises from the fascia posterior to the branchial 

 arches, and appears to be attached slightly along its entire 

 course down the arm to the phalanges. From the obliquus 

 externus a band of fibres runs forward to its insertion in the 

 upper part of the humerus, serving to draw the arm backward. 

 This muscle corresponds to the latissimus dorsi. Another 

 muscle arising in common with the last mentioned is inserted 

 along the middle portion of the humerus, sending fibres on- 

 ward to the phalanges, and is probably the atrophied remains 

 of the infraspinatus. Owing to the fact that AmpJiiinna seldom 

 bends its arm at the elbow, the muscles arising from the 

 shoulder region in many instances continue to the forearm 

 and hand. This is the primitive condition of limb muscles. 

 In fact, I do not think this animal is capable of flexing the fore- 

 arm or the arm, as the muscles are so bound together by dense 

 fascia and continnons at the elboiv joint. My anatojnical infer- 

 ence on this point was confirmed by observing a large specimen 

 moving across the floor. The limbs did not touch tJie floor, but 



