424 DR. J. MURIE ON THE ANATOMY OF THE WALRUS. 
8. Pelvic Limb, and Comparison with that of Seal.—According to whether the hind foot 
is opened or closed so does the appearance of the free portion of the limb vary. Dorsally, 
when closed (see fig. 10, Pl. LIII.), it is long, parallel-sided, with the first and fifth 
digits conspicuously elongated, and the three shorter median ones overlapping each 
other as well as those on either side. The fifth digit is the largest of all, in this respect 
agreeing with Phoca, but differing from 0. jubata, where the first or great toe attains 
the maximum dimensions. If figs. 2 & 4, pl. iv. Phil. Trans. 1824, be compared with 
the present fig. 10, it will be seen that the first and fifth digital extension are incurved. 
This is quite a possible circumstance, as beyond the bony phalanx there is a soft carti- 
laginous tip. I must state, however, both from a study of the live animal and manipu- 
lation of it when dead, that incurvation and close proximity of the ends of the first and 
fifth digits is an unnatural position for them to assume, and only results from alteration 
of the textures or from force. 
The amount of loose interdigital membrane is very considerable, so that when ex- 
panded the foot is fan-shaped. The dorsal surface is smooth compared with the 
plantar one. ‘The sole, indeed, like that of the manus, is rough and gnarled. From 
the os calcis forwards to the proximal ends of the digits there are several deep trans- 
verse furrows, and, besides, innumerable smaller sinuous gyrations, forming altogether a 
scabrous pad. This rough rasp-like condition has not been delineated by Home (J. c. 
pl. iv. figs. 3 & 4); but he correctly represents a fleshy ridge running from behind for- 
wards between the third and fourth digits. Of the concavity or disk whereby adhesion 
by suction to the ground is performed, and by this mechanism the Walrus is enabled to 
support its gravity in progressive motion, I coincide with Von Baer, who regards Sir 
Everard Home’s notion as untenable. No one who has ever seen the Walrus walk, or 
the Otaria climb (and they are both capable of the latter extraordinary movement), 
could for a moment suppose that by a pedal vacuum, as in a fly’s foot, the massive 
Pinnipedian was sustained. 
Returning, however, to the general aspect and tegumentary attachment of the entire 
pelvic limb, I shall, as in the pectoral extremity, institute a comparison of it chiefly 
with that of the Seal (Phoca). 
In the Walrus the hind quarters seem shorter than in the Seal, apparently because 
of the different proportion between the femur and the tibia and fibula, the greater 
comparative length of the femur in the Walrus producing an expanded breadth opposite 
the iliac bones as the animal thrusts the femur outwards; this at times also gives a less- 
arched form to the hinder parts in the Walrus, whereas in the Seal, from the tibia and 
fibula being more fixed, there is a greater lateral compression at the sacral and distal 
end of the caudal region. In the Seal the ossa calcium, or rather heels, approach close 
to the tail, and cannot be thrust outwards far from it, whereas in the Walrus, while they 
can be pushed in towards the tail with ease, or even join one another, they at the same 
time can be separated as much as, or even more than, a foot distant from each other, 
