ITS STRUCTURE, BULK, AND ASPECT. 95 



Fig. 49. 



tion. In one of my specimens a few fragments of the raya 

 are preserved (fig. 49, b.) They are 

 about the eighth part of an inch in dia- 

 meter ; depressed in some cases in the 

 centre, as if, over the internal hollow , 

 formed by the decay of the cartilaginous 

 centre, the bony crust of which they are " ^ ThcmrJbnck ^^^ 

 composed had given way ; and, like the h. Single joint of ray of 

 rays of the thornback, they are thickened 

 at the joints, and at the processes by which they were at- 

 tached to the ischiatic base. It may be proper I should here 

 state, that of some of the internal bones figured above I have 

 no better evidence that they belonged to the Asterolepis, than 

 that they occur in the same beds with the dermal plates which 

 bear the characteristic star-like markings, — that they are of 

 Fig. 50. 



COPKOLITES OF ASTEROLEPIS. 



(,Nat. size.*) 



• One of the Thurso coproHtes in my possession is about one-fourth 

 longer than the larger of th«» two specimens figured here, and nearly thrioa 

 M broad. 



