FORE-LIMB. 131 



C. 155. Right fore-limb of a Seal (Phoca vitulina), showing the 

 superficial muscles. The adaptation of the limb to a 

 swimming life is shown in its musculature by the high 

 development of the rotator muscles, especially those of 

 pronation. During the backward stroke the palmar surface 

 of the hand is turned outwards by the action of the usual 

 pronator muscles assisted by some of the flexors (flexor 

 carpi ulnaris, palmaris longus) which run from the point 

 of the elbow towards the radial margin of the hand. At 

 the same time the digits are spread by an abductor minimi 

 digiti arising from the elbow, and inserted in the subcuta- 

 neous tissue on the outer side of the little finger. Supina- 

 tion takes place during the recovery, whereby the narrow 

 anterior border of the limb is turned to the front and offers 

 the minimum of resistance to the water. In this action the 

 usual supinators are assisted by the extensor pollicis brevis 

 and extensor ossis metacarpi pollicis. The following 

 muscles show exceptional features : A fasciculus of the 

 extensor antebrachii (marked * in the specimen) rising 

 from the vertebral end of the scapula posterior to the spine 

 and inserted partly into the elbow, partly into the abductor 

 minimi digiti (it is sometimes called dorso-epitrochlearis, 

 but this name seems better applicable to a tendinous strand 

 running from the latissimus dorsi to the internal condj-le). 

 The latissimus dorsi is in two parts one inserted into the 

 teres major, the other into the outer bicipital ridge with 

 the pectoralis major. The extensor digitorum communis is 

 double. 



C. 156. Left fore-limb of a Seal (Phoca vitulina), showing the 

 deep muscles. There is a small sabscapularis accessorius, 

 which rises from the posterior border of the scapula near 

 the glenoid and is inserted into the joint-capsule and upper 

 part of the humerus. 



Miller, Challenger Reports, Zool. vol. xxvi. 1888, p. 142 ; 

 Lucae, Abhandl. Senckenberg. Naturf. Gresellsch., 

 Bd. ix. 1873-75, p. 474. 



C. 157. Right humerus and part of the fore-arm of a Dog (Canis 

 familiaris), showing the brachialis in,ternus. The muscle is 



K2 



