Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/772

 Such is the general character of this peculiar scaly armature. Not much, however, of the external surface is seen ; but a portion of two or three rows of the scales is well displayed at the anterior extremity of the ribs on the right slab, or that on which the coronal portion of the cranium is preserved. This patch of the scaly covering of course belongs really to the left side of the animal ; it overlies the ribs, and in part covers the bony mass, which we suppose may be the remains of the shoulder-girdle. Other two considerable patches are observed overlying the ribs near the centre of the body, and several smaller patches are scattered over the specimen. All these patches exhibit the minute striation of the surface, and that in front displays also the ribbed structure ; and the casts of all of them can be traced on the left slab. That of the anterior patch is well marked, and is of considerable extent, showing both the ridges and the minute striation of the surface.

Upon the left slab, too, the under surface of the scales is well seen, particularly a belt of a portion of four or five rows about an inch wide, that stretches along by the side of the vertebral column. And towards the posterior extremity of the specimen, the rows of scales are seen in their whole length (i, i) extending in parallel order from the ventral to the dorsal margin, sloping forwards, and crossed by the ribs which incline in the opposite direction. The inside of the rows of the scales is equally well displayed on the right slab.

The scales themselves (fig. 3) are rhombiform, with the angles slightly rounded, and having projecting from the lower anterior angle a strong, pointed conical process, which is overlapped by the dorsal margin of the scale next below. They are transversely elongated, and measure in this direction an inch and three-quarters, lengthwise, or from the anterior to the posterior margin, five-eighths of an inch. We shall, however, merely for the sake of convenience, consider the long measurement as that of the length, the short as that of the width.

The ends, then, of the scales are truncated diagonally from above downwards and backwards ; they (the scutes) are rather stout, but gradually thin out to the margins, which are very fine, and have a widish, thick ridge extending the whole length, much nearer to the front than the posterior margin, and parallel to it. This ridge is smooth and rounded below, where it is seen to be continued into the projecting process ; above, on the outer surface, it forms an obtuse ridge the entire length of the scale. The anterior part of the outer surface is smooth as far back as this ridge, and is bevelled or sloped to the margin ; the posterior portion is twice as wide as the smooth anterior border, and slopes or inclines in the opposite direction or backwards, so that the longitudinal carina is like the ridge of a very low-pitched roof with one of the slopes much shorter than the other. The wide posterior slope is minutely and closely striated, the striae being raised, sharply defined, and slightly diagonal from above downwards and backwards, and are somewhat broken and tortuous.

The scales imbricate backwards, the anterior overlapping the