428 DESCRIPTION OF THE MUSEUM. 



habit our coasts, but it is only lately that they 

 have been distinguished from their congeners. 



The other species of the genus ray have the 

 body extremely depressed, and very wide, with 

 a long filiform tail. Their teeth, which are of 

 different forms, serve to distinguish the sub- 

 genera; in certain species the tail is smooth, in 

 others it is armed with long prickles, furnished 

 on each side with very deep notches These 

 weapons are not venomous, but they inflict 

 wounds which it is very difficult to cure. 



The thorn-back (raja clavata), and the rough 

 ray (r. rubus], which are common in our mar- 

 kets, are the species most esteemed as food. 



Of those which inhabit our seas, the skate 

 (raja batis, Lin.,) arrives at the greatest size; it 

 has been known to weigh more than two hun- 

 dred pounds. Amongst the foreign species, one 

 of the most remarkable is the pearled ray (r. sjr- 

 rhe7i), which belongs to the sub-genus of the 

 pastinacce ; its body is covered with close set 

 and hard tubercles ; after they have been worn 

 on a millstone, to polish them and render the 

 skin smooth, it is used for covering various kinds 

 of cases, and called shagreen. This species of 

 ray is found on the coast of Coromandel, from 

 whence it was sent by M. Leschenault. 



The Mediterranean furnishes also a gigantic 



