438 DR. J. MURIE ON THE ANATOMY OF THE WALRUS. 
The deep short muscles situated at the back of the neck, as a whole, resemble those 
of the Sea-lion (Otaria); nevertheless, though large in this animal, they are surpassed 
in size in the Walrus. It may be noted respecting the rectus posticus major, that 
besides being attached to the axis it extends backwards, and has attachments to the 
five posterior cervical zygapophyses, and even as far as the first dorsal superior articular 
process. 
The Walrus also has a moderate-sized muscle, representing that depicted by me in the 
Otary, where it is so well developed; this arises in the former from the fourth as well 
as third cervical vertebra, and is inserted into the atloidean transverse process. 
In Cuvier’s ‘ Planches de Myologie’ the apparent representative of this muscle in 
Phoca vitulina (pis. 172 & 173. fig. 2,0) is termed the “long antérieur du cou (prédorso- 
atloidien),” or, as I infer, is taken for an anterior portion of the longus colli. In the two 
first-mentioned genera the longus colli was quite distinct from the belly in question. 
The trachelo-mastoid is an extensive muscle, which seems in the Walrus to cor- 
respond with the same fleshy structure in Man, only of course vastly more developed. 
It arises from the zygapophyses of the anterior five dorsal vertebrae, and from the 
analogous processes of the whole of the cervical vertebra. Posteriorly the muscle is 
divided more or less into slips; but anteriorly it becomes thicker, and finally is inserted, 
by a strong tendon, into the inferior outer side of the paramastoid process. 
Besides fleshy slips sent to the sixth, fifth, fourth, and third cervical vertebrae, the 
longissimus dorsi in 7richechus has extra slips to the seventh and the second cervicals. 
In the Morse the spinalis dorsi goes to the spine of the sixth cervical vertebra, whereas 
in the Sea-lion it reaches no further than the first dorsal spine. 
Splenii—These, comparatively, are not nearly so large as in the Eared Seal. What 
answers to the splenius capitis is thin but broad; it arises backwards about as far as 
the fourth or fifth dorsal spine, and, becoming slightly thicker in the neck, is inserted 
into the occipital region. The representative of the splenius colli seems to be only a 
thin narrow slip, coming from the fifth and sixth dorsal spines, and inserted, to the 
outer side of the occipital region, towards the paramastoid. 
What I take as the homologues of the complexus and biventer cervicis differ some- 
what from what obtains in Ofaria. The complexus appears to arise from the zygapo- 
physis of the fifth anterior dorsal vertebra, and, as it proceeds to be inserted into the 
spine of the occiput, is joined by the next-mentioned muscle. What answers to the 
biventer cervicis is a longer, narrower, and thicker slip arising from the zygapophysis of 
the seventh dorsal. 
Rhomboidei.—Precise limiting divisions between the rhomboideus capitis, rhomboideus 
major, and rhomboideus minor are with difficulty made out in 7richechus, as, to a certain 
extent, is the case in Otaria jubata. 
If, however, in the former animal the posterior portion be taken as the rhomboideus 
minor, then it agrees with the description of this muscle in the latter animal. It does 
