504 DR. J. MURIE ON THE ANATOMY OF THE SEA-LION. 
age; for I find such symphysial cartilaginous union obtains, not only in the adult speci- 
mens of Otaria jubata, but even in undoubted old animals of the same species. Each 
body possesses a shallow curve, the concavity of which looks inwards; and the halves 
together thus form a tongue-shaped arch, ending in front in the broadish deep sym- 
physis. Immediately beneath the well-marked incisor-fossee and foramina, the edges of 
the symphysis pout forwards in a low but distinct median mental crest, some half an 
inch in vertical depth. Below this the rami gradually diverge from each other, inclining 
downwards and backwards as they each form a thickened posterior symphysial angle. 
The extreme length of the lower jaw measures 7°25 inches; the greatest diameter 
(which is at the condyles) is 5-3 inches. 
A row of foramina as numerous as the molar teeth on the left side, and less by one on 
the right, occupy a line trending downwards from the alveolus, opposite the last molar, 
to below the middle of the bone, and anteriorly vertical between the first and second 
molar teeth. The most anterior of these is the largest, and may represent the mental 
foramen of Man; but here, in the Sea-lion, the vascular supply is great, and accord- 
ingly supplied with an increased number of nutritious channels. A narrowing and 
thinning of the bone distinguishes or separates the body from the ramus; this nearly 
median contraction has the effect of giving the side of the jaw a somewhat long and 
irregularly bordered figure-of-eight contour. At this narrowest part, just behind the 
last molar, there is a breadth or vertical depth of 1:2 inch, and a thickness of 0-4. 
From it the ramus commences, and very gradually widens, its thin coronoid lamina 
rising at an obtuse angle to the body. The angle, a flattened rhombic plate, is inflect, 
with a deepish emargination in front. The condyloid neck is compressed antero- 
posteriorly. 
d. Foramina of Lower Base'.—The anterior palatine are fissures of some magnitude. 
Marked postpalatine foramina do not obtain ; but instead a linear series of minute open- 
ings reach from opposite each penultimate tooth back to the end of the maxillary splint, 
in apposition with the lengthened palatal arch. ‘There is an alisphenoid canal per- 
forating longitudinally the base of the pterygoid, and communicating with the spheno- 
orbitary region. A Vidian canal, admitting a fine bristle, can be traced along the inside 
of the pterygoid root. A fair-sized foramen ovale lies behind and outside the alisphe- 
noid canal; and exterior to it is the postglenoid foramen. Directly posterior to the 
ovale, and in a somewhat irregular transverse recess, there are close together the lacerum 
medium, anterior opening of the carotic canal, hiatus Fallopii, and fissura Glasseri—the 
said recess, moreover, being surmounted posteriorly by the tubercle developed in front 
of the tympanic. The orifice of the meatus auditorius externus is sunk in a conical 
hollow between the mastoid eminence and the tympanic bulla, the large stylomastoid 
foramen being situate close to its rear. Still further back, and more towards the 
‘ Compare respectively the interesting researches on this subject in the Carnivora by H. N. Turner, as cited, 
and Prof. Flower, P. Z. 8. 1869, p. 4; also Prof. Owen’s pithy descriptive remarks on specimens in the Hun- 
terian Museum, 
