316 CARTILAGINEI. — RAIAD^. 



Ray, the whole canal of whose infestine is not 

 more than half as long as the stomach." 



3. Raiana, The Skates. The rhomboidal or 

 lozenge-shaped outline, is eminently character- 

 istic of this group, which is the most numerous 

 of the whole. The tail is moderately long and 

 slender ; furnished with two small dorsals, and 

 generally terminated by a small caudal. The 

 skin on the upper parts, particularly of the tail, 

 is generally studded with asperities, tubercles, or 

 curved prickles, but never armed with a long, 

 serrated bony spine. Eleven of our British spe- 

 cies belong to this group. 



4. Trygonina. The Sting-rays. In these the 

 head is surrounded and inclosed by the pectoral 

 fins ; the disk is somewhat rounded ; the tail is 

 long, and drawn out to a fine point ; it is quite 

 destitute of fins, but is armed near its base with 

 a long and sharp, flattened, bony spine, the two 

 sides of which form thin edges, cut into close, acute 

 teeth, — a most formidable weapon. We have one 

 British species, commonly called the Fire-flaire, 

 of which Mr. Couch thus speaks. " The man- 

 ner in which it defends itself shows its conscious- 

 ness of the formidable weapon it carries on its 

 tail. When seized or terrified, its habit is to 

 twist its long, slender, and fiexible tail round 

 the object of attack, and with the serrated spine 

 tear the surface, lacerating it in a manner calcu- 

 lated to produce violent inflammation." Other 

 authors state that it is capable of striking its 

 weapon with the swiftness of an arrow into its 

 prey or its enemy, when, with its winding tail, 

 it secures its capture. 



5. Myliohatina, The Eagle Rays. The pec- 



