238 Description of the Chlamyphorus truncatua. 



half, extending about one half round the body ; this covering 

 is loose throughout, excepting along the spine of the back and 

 top of the head ; being attached to the back immediately 

 above the spine, by a loose cuticular production, and by two 

 remarkable bony processes (to be described hereafter) on the 

 top of the os frontis, by means of two large plates, which are 

 nearly incorporated with the bone beneath ; but for this at- 

 tachment, and the tail being firmly curved beneath the belly, 

 the covering would be very easily detached. The number of 

 rows of plates on the back, counting from the vertex, (where 

 they commence) is twenty-four ; at the twenty-fourth the shell 

 curves suddenly downwards, so as to form a right angle with 

 the body ; this truncated surface is composed of plates nearly 

 similar to those of the back ; they are disposed in semicircular 

 rows, five in number : the lower margin, somewhat elliptical, 

 presents a notch in its centre, in which is attached the free 

 portion of tail, which makes an abrupt curvature, and runs 

 beneath the belly parallel to the axis of the body ; the free 

 portion of tail consists of fourteen caudal vertebrae, surround- 

 ed by as many plates, similar to those of the body; the ex- 

 tremity of the tail being depressed, so as to form a paddle ; 

 the rest of the tail compressed. The caudal vertebras extend 

 up to the top of the back, beneath the truncated surface, where 

 the sacrum is bent to meet the tail. The superior semicircular 

 margin of the truncated surface, together with the lateral 

 margins of the shell, are beautifully fringed with silky hair. 



Head : posterior half, broad, anterior half, before the eyes, 

 tapering ; the occiput is covered by the five first rows of the 

 back plates, with which they are continuous; the occiput not 

 distinguishable externally. The anterior half of the top of 

 the head, is covered, first, by a row of large plates, five in 

 number, which are firmly attached to the bone beneath ; par- 

 ticularly the two outer ; — secondly, by a smaller row, six in 

 number, anterior to which, that is to say, the top of the snout, 

 is covered with smaller plates irregularly disposed. 



