228 ■ MESSRS. HANCOCK AND HOWSE ON A 



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 con- 

 siderable extent, showing both the ridges and the minute stria- 

 tion 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 trans- 

 versely 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 sur- 

 face, 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 



