DR. J. MURIE ON THE ANATOMY OF THE SEA-LION. 511 
facet, together nearly 3 an inch long, in this and the succeeding rib, shoot upwards 
nearly in the line of the axis of the body itself. Indeed these processes seem almost 
to form the true termination of the ribs, from which the neck and head proper seem 
but forked offsets. 
The second rib diverges slightly from the pattern of the first, inasmuch as it is rather 
longer, thinner, and possesses a wider sweep or curvature from the angle to the neck. 
There is just a perceptible indication of a bending backwards or semi-twist at the angle, 
but not the same flattening and bulging which obtains in the succeeding ribs. ‘The 
scalene tuberosity, tolerably well marked in the first rib, is diminished and well-nigh 
obsolete on the second. 
The third, fourth, and fifth ribs are fashioned not unlike each other, and with but 
slight individual variation. They present different yet scarcely appreciable degrees of 
curvature and twist, the body altering in such a manner that what was the anterior 
surface in the first and second ribs becomes in them the outer flattened surface, 
Their sternal extremities are more compressed and elliptical in outline than the ribs in 
front or those immediately behind. The angles of the three ribs in question are better 
indicated than the others in the series, but none have it well pronounced. ‘The fork- 
like head and elongated tubercle distinctive of the first two ribs undergoes a gradual 
change in the third, fourth, and fifth. The neck becomes vertically deeper, less con- 
stricted, and consequently appears shorter, although not in reality so. The tubercle 
diminishes in length, and its articular facet acquires a more backward direction. The 
anterior groove at the angle lessens from the third to the fifth. The enlarged capi- 
tulum of each assumes an obliquity of condition, and with a fore-and-aft articulating 
face abuts upon the posterior surface of the body of the vertebre in advance and the 
anterior surface of its own numerical vertebra. From the sixth to the twelfth costal 
elements there is a very gradual progressive change in the amount of curvature, and in 
reduction of the tubercle. The differences between the intervening ribs will be best 
comprehended by comparing, say, the sixth with the twelfth, rather than attempting to 
describe the next to insensible modifications which the ribs seriatim undergo. 
The sixth rib, then, with similitude to the fifth, is long, of moderate breadth and 
thickness, narrowed and slightly triangular in transverse section about its middle, but 
flatter and compressed from within outwards, below. It joins the sternal cartilage by 
a truncated somewhat bulbous end. The outer surface from the angle downwards 
is plain and smooth, the front and hinder edges gently rounded. The unequal arch of 
the body is deepest at the angle. The latter is not protuberant but definable, the more 
readily so as the rib at this part as well as the neck and head is compressed antero- 
posteriorly. The tubercle is of fair size; the neck and head large, but uniform in 
diameter. The most notable changes in the twelfth rib are little or no antero-posterior 
compression, no defined angle, the rib from one end to the other presenting a wide, 
low, regular arch. The head, neck, and tubercle have decreased in ratio, the division 
4B2 
