DE. J. MUBIE ON THE ANATOMY OF THE SEA-LION. 545 



to the distal end of the metatarsal, splits, and supplies the adjoining sides of the first and 

 second toe. At the proximal end of' the second metatarsal, what in Otaria is equiva- 

 lent to the external plantar in Man, springs from it, then a little way on again divides, 

 a third outer branch coming off still further on. These three bifurcate and give twigs 

 to the second and third, the third and fourth, and the fourth and fifth toes respectively. 

 The outside of the fifth toe receives a separate twig derived from the peroneal near the 

 calcaneum. 



Internal Iliac. — Its divisions within the pelvis were not noted with sufficient exactness. 

 One artery, however, has very unusual relations, if, as seems the case, it is the homo- 

 logue of the sciatic and its derivative comes nervi ischiadici. This vessel, of considerable 

 calibre, accompanies the sacral plexus through the sciatic foramen, and afterwards fol- 

 lows the course of and bears relations similar to the lesser sciatic nerve, already de- 

 scribed. It yields branches to the large lymphatic gland in the tibio-caudal space, to 

 the semitendinosus, membranosus, sacro-peronaeus, and other muscles of the back of the 

 leg, and proceeds on to the outer ankle. 



3. The Venous Blood-channels. 



The veins derived from the interior of the cranium, the head, face, tongue, and fauces, 

 combining, form the external and internal jugulars. Small veins come from the thyroid 

 gland, the omohyoid, and neighbouring parts below the cricoid cartilage ; these unite 

 into a common vein, which joins the internal jugular opposite the lower posterior 

 extremity of the thyroid gland. 



The recurrent venous channels from the hind limbs and pelvis forming the posterior 

 vena cava are of great calibre, and particularly so after receiving the renal veins. These 

 latter emulgent veins are of unequal length, the left being the longer of the two : com- 

 pared with the kidney itself, they are of inordinate capacity. 



The portal vein, on reaching the flat portion of the liver or bridge connecting the 

 Spigelian and right lobes, divides into two great main trunks. The short one of these 

 supplies the right or i lobe. The other, which is set at a wide angle from the last, 

 proceeds upwards and to the left, sending off wide branches and smaller divisions to the 

 several large lobes, viz. ii, iii, iv, v. Each branch is accompanied by a derivative twig 

 from the hepatic artery ; the veins, however, are by very far the larger. 



By far the most remarkable point in connexion with the venous system is the en- 

 largement of the posterior vena cava or great hepatic sinuses so admirably depicted by 

 Barkow ' in the Common Seal, Phoca vitulina, and similar to those of the Walrus. It 

 is in fact but a simple expansion of the vena cava within the precincts of the liver, and 



' Professor Barkow's magniflcent illustrations of the vascular system contain several devoted to Phoca vitu- 

 lina, P. annellata, and HaUchcerus griseus ; but a comparison with these is beyond the limits of the present 

 paper. ' Die Blutgefasse, &c.' Breslau : see plates x. to xiii. and xxix. 



