406 THE ANATOMY OF VEETEBKATED ANIMALS. 



The cutaneous muscle is very largely developed and lies 

 between two layers of blubber, the thick superficial one 

 separating it from the skin, and the thin deep layer from 

 the subjacent muscles. It may be said to be disposed in two 

 broad layers, a dorsal and a ventral, on each side ; these 

 extend from the occipital crest, and from the rami of the 

 mandibles, to the tail. Both these divisions send off strong 

 bundles to the humerus, which act as powerful adductors, 

 abductors, protractors, and retractors of the fin. There is 

 no trapezius, and the representative of the latissimus dorsi 

 is very small. A strong occipito-humeralis, from the para- 

 mastoid to the tuberosity of the humerus, seems to repre- 

 sent the cleido-mastoid and clavicular deltoid. A costo- 

 humeralis extends from the sternum to the inner tuberosity 

 of the humeiiis. A small coraco-hrachialis extends from 

 the apex of the coracoid to the inner tuberosity of the 

 humerus. The pectoralis major seems to be represented by 

 a muscle which arises from the sternum, close to the attach- 

 ment of the third and fourth ribs, and is inserted into the 

 ulna. The triceps extensor is represented by tendinous fibres 

 in which muscle cannot always be detected, which extend 

 from the posterior face of the humerus to the idna. The 

 other muscles of the fore-arm and all those of the manus 

 are absent. The dorsal muscles form a thick continuous 

 mass from the end of the tail to the occiput; and, on the 

 ventral side of the spinal column, the subcaudal muscles 

 are similarly continued forwards, as far as the middle of the 

 thorax. An ischio-caudalis passes, on each side, from the 

 anterior chevi-on bones to the ischium. Between their 

 attachments is an aponeurosis which supports the anus ; 

 ischio-cavernous muscles pass from the ischia to the corpora 

 cavernosa. 



The diaphragm has no tendinous centre. Its pillars are 

 very thin, and, extending between the kidneys and the spine, 

 become tendinous, and are attached to the ventral faces of 

 the vertebrae, as far as the ninth lumbar. A strong fibrous 

 aponeurosis is continued back over the subvertebral muscles 

 to the pelvic bones. Between these bones and the ends of 



