DR. J. MURIE ON THE ANATOMY OF THE WALRUS. 451 
psoas magnus, although upon the whole these two muscles are closely united; at their 
insertion there can only be said to be a single tendon. The portion corresponding 
to the psoas parvus is decidedly weaker relatively than in the Eared Seal. The other 
part, or psoas magnus, is thin, and has origin by two narrow tendons,—the first of 
these from the last rib, just outside the quadratus lumborum; the second from the body 
of the second lumbar vertebra, close to where the tendon of the psoas parvus arises: 
there is also a muscular origin from the bodies of the fourth and fifth lumbar vertebre. 
The united psoas magnus and psoas parvus is rather longer in Ofaria, and is attached 
to the ilio-pectineal eminence. 
A slightly different arrangement of the muscular bundles of the quadratus lumborum 
prevails. ‘The most anterior slips have origin from the last dorsal vertebra. The 
double slip in question comes partly from the ventral and partly from the lateral 
superficies, the outer portion covering the head of the rib; the inner portion passes 
down to the tip of the transverse process of the second lumbar vertebra. Behind this 
there come, in a V-shaped manner, three muscular slips which unite and send on a 
tendon which is inserted into the tip of the transverse process of the third lumbar 
vertebra. The outermost of these three slips, fleshy, comes from the last rib and out- 
side muscle already described. The second and third slips come close together from 
the body and side of the second lumbar vertebra. In a similar manner there is an 
outer slip from the transverse process of the second lumbar, and an inner fleshy head 
from the body of the third lumbar vertebra, uniting into a single tendon which is 
inserted into the transverse process of the fourth lumbar vertebra. 
According to Duvernoy’s’ interpretation of the functions performed by the inferior 
loin-muscles in Phoca vitulina, it is to the psoas chiefly that the peculiar belly-pro- 
gression on land is due. ‘There can be no doubt that the pelvic insertion of the com- 
bined psoas must have considerable influence; but while inclined to agree with him, I 
even lay more stress on the power exercised by the panniculus (his sacro-humérien) and 
belly-muscles generally on the movements in question. He states that the iliacus is 
absent”; but the result of my examinations of species of Phoca coincides with Meckel’s* 
and Humphry’s‘—namely, the presence of a diminutive representative of the muscle, 
such, indeed, as has been figured by Cuvier and Laurillard (‘ Myologie,’ pls. 169, 170. 
fig. 3,7). A semidivided fair-sized iliacus is decidedly met with in the Morse and Otary. 
So far as my dissection of the parts enabled me to judge, the caudal muscles differed 
little from the condition existent in the Otary. The levator caude externus and 
internus had each a long narrow fusiform belly and a short strongish flattened tendon. 
The pubo- and ilio-coccygeus were but moderately fleshy, as likewise was the ischio- 
coccygeus, the tendons of the latter being much interwoven and strongly bound down 
by aponeurotic fascia. 
* «Sur les Organes du Mouvement,” /. c. p. 185. cial Spit cto fae bP 
* Anat. Comp. vol. vi. p. 371. * Paper quoted, p, 309. 
VOL. VII.—PART VI. June, 1871. 3R 
