DR. J. MURIE ON THE ANATOMY OF THE WALRUS. 445 
deltoid ridge. The second portion of the deltoid, barely separated by a line of demarca- 
tion from the first, is otherwise exactly the counterpart of that of the Sea-lion. 
Dorso-epitrochlear (woodcuts, figs. 3 & 4, D.ep).—This muscle (apparently the M. 
tricipiti-accessorius of Professor Haughton in the common Seal’) is in the Morse almost 
entirely separate, and does not overlap the first head of the triceps as in the Otary. It 
arises from the scapula, between the infraspinatus and teres major, at the inferior 
posterior border of the bone, and passes down, only as a moderately broadish fleshy 
band, on the surface of the scapular division of the triceps towards the olecranon 
process; but it is attached to that bone by fascia alone; for its muscular fibres are 
continued on to the posterior border of the forearm as far as its middle, where they 
are fixed to the antibrachial superficial fascia over the muscle. 
The triceps (woodcuts, figs. 3 & 4, 7", T°, T°) is almost identical with that of O. jubata, 
the scapular head, however, as above mentioned, being outwardly less covered by the 
dorso-epitrochlear. 
In the Walrus, as in the Sea-lion, there are well-developed anconeus externus 
(woodcut, fig. 3, 4.e) and anconeus internus (woodcut, fig. 4, 4.7) muscles present. 
The latter is occasionally found as an abnormality in Man. Mr. Wood, in his inter- 
esting “ Variations in Human Myology”?, names it “anconeus epitrochlearis;” but it 
had already been recognized in Cuvier and Laurillard’s ‘ Recueil’ as “ anconé interne, w' 
(€épicondylo-cubitien).” 
The infraspinatus overlaps its bony fossa (woodcut, fig. 3, Isp). ‘The supraspinatus 
(woodcut, fig. 4, Ssp) has a single insertion. 
I have described in the Otary a superficial semidifferentiated portion of the sub- 
scapularis in close conjunction with the supraspinatus as traversing obliquely the 
former muscle, and quite covering its insertion ; it is itself fixed into the capsular ligament 
and inner humeral tuberosity. This, for distinction’s sake, I have termed epi-subscapu- 
laris. In the Walrus there is a similar superincumbent layer of the subscapularis 
present (see woodcut, fig. 4, Zp.s); the fibres of which, however, are not so curvilinear 
as in the Otary, rather running parallel with those of the deeper subscapularis, but 
inserted quite into the top of the ulnar tuberosity. 
The humeral insertion of the teres major (woodcut, fig. 4, 7.ma) is to the inner side 
of that of the latissimus dorsi. 
If present, the teres minor is rather indistinct. 
The Walrus differs from the Eared Seal (0. jubata) in the possession of a coraco-bra- 
chialis, which in the latter is absent, or its place supplied by a slight extension of a portion 
of the extra supraspinatus. This coraco-brachialis (woodcut, fig. 4, C.b) arises by a long 
narrow tendon from the glenoid capsule, and, forming in the length of the humeral shaft 
a weak belly, is continued by muscular fibre as far as the distal end of the internal lateral 
ligament of the elbow. The musculo-spiral nerve pierces the few fleshy fibres present. 
1 Loe, cit. p. 40. * Proc. Roy. Soc. 1867, vol. xv. p. 522. 
VOL. VII.—PART VI. June, 1871. 
Go 
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