DR. J. MURIE ON THE ANATOMY OF THE SEA-LION. 543 
ficial to and mingling with the compressor, fastens itself to the alar and other cartilages 
at the side and fore part of the nostrils. 
I regard as the depressor ale nasi (D.a.n, D.a.n*) a powerful muscular band which 
springs from the bone in front and beneath the infraorbital foramen. Running along 
the superior labial margin in company with and overlapping the orbicularis oris, it 
proceeds to the front of the muzzle, and is inserted by tendon into the premaxillary 
bone, whilst fleshy bundles grasp the alar fibro-cartilage and intertwine, as aforesaid, 
with the dilatator naris. 
The orbicularis oris (0.0) is of fair volume, and, as usual, surrounds the mouth ; its 
fibres are somewhat thicker at their fore part, and, doubtless, include the homologues of 
the inferior labial group. 
Action. ‘There is a certain amount of consentaneous contractility among the whole 
of the Sea-lion’s facial muscles, the cross direction of the superincumbent planes pro- 
ducing a diagonal of force. Nevertheless, though this is the case, yet each set, as the 
names imply, perform a separate office. The levator labii superioris aleque nasi, 
levator anguli oris, and zygomatici, together, chiefly drag back the upper lip in snarling, 
an expressive action added to by the retraction of the inferior labial group. ‘Tension 
of the compressor naris most effectually closes each orifice and retains it so, possibly 
aided by the counteracting efforts of the depressor ale nasi. The wide, patulous con- 
dition which the nostrils at times assume, of some moment and interest as far as 
characteristic feature is concerned, is indubitably produced through the long leverage 
of the dilatator. The mass of flesh, the numerous vibrissee, and the skin composing 
the muzzle and snout are plentifully supplied with nerves (Jon) and vessels, which 
come in a great bundle from the infraorbital foramen, and pursue a course straight 
forwards and underneath the dilatator. / 
As in Carnivora generally, the buccinator (figs. 15 & 16, Bu) is fleshy, and has attach- 
ments upon the upper and lower jaws, close to the alveoli. Behind, it comes from the 
pterygo-maxillary ligament; and in front the fibres reach forwards as far as the anterior 
premolars. 
Temporal Muscle.—This is of large size, and consists of a partial double layer, the 
upper one mingling with a deep layer of the double masseter. 
The main portion of the temporal muscle (Ze', Ze", figs. 15 & 16) lies on the tem- 
poral and parietal bones, filling with fan-shaped fleshy fibres in great part the temporal 
fossa as high as the temporal ridge. This so-called first portion of the muscle is inserted 
into the coronoid process of the mandible. 
The second and superficial portion of the muscle (7e’) is semilunar in outline, its 
concavity being directed backwards, and one (the anterior) horn reaching above but 
behind the orbit. This second portion arises upon the surface of the first and deeper 
portion, the fibres of the former freely intermingling with the latter. It also has origin 
from the inner surface of the zygomatic arch, at the posterior part of which it is par- 
VOL. VII.—PART vill. January, 1872. 41 
