DR. J. MURIE ON THE ANATOMY OF THE SEA-LION. 535 
posteriorly, and about 3'5 of an inch wide. ‘The fibres are not perfectly circular, but 
are seen to be derived from the radii of the dilator, and as they approach the pupil to 
interlace and proceed to the edge obliquely. The ciliary muscle is well developed. 
The venous meshwork constituting the canal of Schlem has considerable volume. 
The ciliary processes of the iris are between 90 and 100 in number. The crystalline 
lens, half an inch in diameter, is nearly spherical or with a very limited antero-posterior 
flattening. ‘The capsule and suspensory ligament are both strong and well developed. 
The optic nerve pierces the eyeball 0-2 inch below its centre. 
b. Orbital Muscles.—Of these a retractor, or what may represent the levator palpebre 
and tensor tarsi,is a broadish thin sheet in intimate union with the superior rectus; 
it separates at the fore part of the eyeball, passes over the superior oblique, and then 
is lost among the circular fibres of the orbicularis palpebrarum. A few of its fasciculi 
join with the superior oblique and internal rectus. Four recti are present; and, as 
usual, the obliqui are two in number. ‘The superior one of these is of moderate 
size, wanting in tendon and pulley, and fleshy almost to its ocular termination. It runs 
obliquely, as a broad band enclosed anteriorly between the rectus superior and 
palpebral retractor; it then turns downwards, outwards, and forwards, to be inserted 
into the middle of the eyeball. At the latter attachment it is overridden by the in- 
ternal rectus, while it covers a slip of the choanoid muscle. ‘The inferior oblique is 
thin and narrow, it is fixed into the globes of the eye, ¢ of an inch below the superior 
oblique. The choanoid or retractor oculi muscle is split into four unequal-sized 
segments. The internal inferior one of these is the most delicate and separated slip. 
Its insertion is below the inferior oblique muscle, just behind it and the lobes of the 
Harderian gland. The upper inner slip is slightly thicker than the former; it passes 
to the back of the globe, and behind the insertion of the superior oblique muscle. The 
two outer portions are much broader muscular sheets, and together in close approxi- 
mation cover the globe for a third of its posterior circumference. 
IV. Tue VascuLar SYSTEM. 
1. Cardiac Receptacle. 
When the muscular organ of the heart is fully distended, or, say, filled with plaster 
of Paris, it appears to be of great proportional bulk to the body; more especially both 
auricles and the right ventricular cavity seem unusually large and protuberant. In the 
flaccid condition it is only of moderate dimensions, namely 63 inches in longitudinal, 
and 5 inches in transverse diameter. The left ventricle measures 5 inches from its root 
to the apex. The form of the heart as a whole is flat, broad, and obtusely pointed, 
the apex, indeed, presenting a tendency to bifurcation. The median longitudinal and 
auricular furrows are shallow. ‘The strong fibrous pericardial investment is attached to 
the aorta, 2 inches above its root on the right side, but considerably lower on the left. 
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