THE SKELETON OF THE PORPOISE, 345 



When the tympano-periotio bone and all the facial bones 

 are removed, only two pair of foramina are visible in the base 

 of the skull. The anterior pair give exit to the second, third, 

 fourth, the anterior division of the fifth and the sixth nerves, 

 and these ansvrer to the optic and sphenorbital foramina. The 

 posterior pair take the place of the oval, posterior lacerated, 

 and jugular foramina, and the precondyloid foramina open into 

 them posteriorly. The rami of the mandibles are only united 

 by a short symphysis. The body of the hyoid is broad and 

 hexagonal, and has two slender, anterior, and two broad and 

 flat, posterior, cornua. 



In the natural position the fore-limbs stand out from the 

 body with their flat surfaces looking upward and downward ; 

 the upper surface being directed a little backward, and the 

 lower a little forward. The tuberosity of the short humerus 

 is directed forward. The carpus contains six or seven ossifica- 

 tions. The number of phalanges in the digits is two, eight, 

 six, three, two, counting the pollex as the first. 



The pelvic bones are elongated, slightly curved, osseous 

 styles. They lie with their long axes parallel to the vertebral 

 column, their convex sides upward, and their smaller ends for- 

 ward, within an inch of the centra of the vertebras, their 

 hinder-ends being close to the third chevron-bone of the tail. 

 The front-ends are about an inch apart. Behind its centre, 

 each bone presents a flattened thickening for the attachment 

 of the corpus cavemosum of its side. 



The cutaneous muscle is very largely developed, and lies 

 between two layers of blubber, the thick surperficial one sepa- 

 rating it from the skin, and the thin deep layer from the subja- 

 cent 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 hu- 

 merus, which act as powerful adductors, abductors, protractors, 

 and retractors of the fin. There is no trapezius, and the rep- 

 resentative of the latissimus dorsi is very small. A strong 

 occipito-humeralis, from the paramastoid to the tuberosity of 

 the humerus, seems to represent the cleido-mastoid and clavicu- 

 lar deltoid. A costo-humeralis extends from the sternum to the 

 inner tuberosity of the humerus. A small coraco-hrachialis ex- 

 tends 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 attachment of 

 the third and fourth ribs, and is inserted into the ulna. The tri- 



