458 DR. J. MURIE ON THE ANATOMY OF THE WALRUS. 
auditory aperture unusually wide and without pinna; 6, eyes small and blood-shot ; 
7, mystacal bristles large, very numerous (and used as a sieve in feeding); 8, nails of 
both pes and manus rudimentary and subequal in size; 9, terminal spatulate cartilage 
of pollex and hallux only moderately developed; 10, proximal ends of soles very rough 
and warty; 11, tip of tongue not bifid; 12, epiglottis exceedingly small; 15, upper cleft 
of thyroid cartilage only slightly cleft, pomum Adami salient and high; 14, ecricoid carti- 
lage relatively deep; 15, the right common carotid artery springs from the aortic arch ; 
16, lobes of liver moderately rounded and superficially sculptured; 17, venous capsular 
sinuses of kidney of medium calibre; 18, meatus urinarius pendulous; 19, presence of 
muscles in fore and hind limbs wanting in other Pinnipedia hitherto examined ; 20, 
variation in form and development of the brain (not fully worked out). 
I am aware such diagnostic items can only be of rough application; but they never- 
theless direct attention to the shades of change observable in a group notorious for 
their similitude in visceral and outward organization. 
The characters distinguishing the marine orders Sirenia and Cetacea from the 
Pinnipedia are numerous and trenchant; and, as several zoologists have shown, these 
groups bear relations to true terrestrial Mammifers, the Ungulata and Carnivora. 
With, therefore, it may be granted, a typical stock or basis which they gradate to or 
from, much interest is attached to the organic modifications whereby the altered 
conditions of life are sustained. The first mentioned three orders, divergent though 
they may be in various ways, similarly exhibit physiological changes coordinate with 
functional activity adapted to a watery element. 
Each and all possess equivalent, though diversified, relations towards their terrestrial 
allies as regards :—1, tegumentary structure; 2, manner of locomotion; 3, circulation ; 
4, vocal and respiratory apparatus; 5, vision; 6, hearing; 7, smell; 8, taste; 9, ali- 
mentary organs; and, lastly, 10, procreation and parts connected therewith. 
The palmar and plantar pads and cushions conspicuously developed and defined in 
digitigrade Carnivores, become less prominent and circumscribed in the plantigrade 
manus and pes, where, though modified, they nevertheless are distinctly present. The 
Walrus’s feet gradate from the Bear’s by the less specialization or line of demarcation 
of the parts in question; and through the former the passage is easy to the smoother- 
surfaced and planer soles of the Earless and Eared Seals. 
The elongate digital nails of the Phocid, with some few exceptions, resemble most 
those of the Urside. The Otaries and Morse agree with, and in the ungual diminution 
and bluntness diverge from the Land-Carnivore type. 
As respects tegument and hair the Walrus stands midway. Unlike the Eared Seals, 
there is no thick underwool or fur; and neither as in them nor as in the Earless Seals is 
the hair itself so short, stiff, straight, and adpressed. The latter group are maneless; 
the males, at least, of the former maned; whilst Walrus has throughout shagygier hair, 
and may be said to be bull-necked. 
