LIST OF FISH. 83 



4. Platyrhina, Mull. & Henle. — The nasal-valve extends beyond 

 the inner corner of the nostril nearly to the middle of the snout, 

 which is obtuse, and the body orbicular, approaching to Torpedo. 



5. Trygonorrhina, Mull. & Henle. — Tail of Rhinobatus, with 

 nose of Trygon. 



III. The Torpedines contain four genera: — 1. Torpedo. — 2 

 Narcine, Mull. & Henle. — 3. Astrape, Mull. & Henle.— 4. Temera, 

 Qray. 



IV. The true Rale contain three genera : — 



1. Raia, Cuv. 



2. Sympterigia, Mull. & Henle. — Tail of Raia; the pectoral-fins, 

 which do not reach the keel of the snout in the true Raja, in this 

 genus extend to the mesial lines, touching each other with their 

 interior edges; the abdominal fin is not divided into two lobes by 

 an incision as it is in Raja. 



3. Uraptera, Mull. & Henle. — Differs from Raja only by the 

 want of a caudal-fin. 



The genus Propleygia, Otto, is founded on a kind of monstrosity, 

 which is not seldom met with in skates. 



V. The Trygons, Cuv., contain the following genera : — 



1. Trygon (Mull. S<, Henle), or Sting Rays. — The teeth are ellip- 

 tical ; the mouth transverse. They are divided into three sub- 

 genera, thus : — 



a. Trygon. — Tail with a fiu above and below. 



b. Hemitrygon. — Tail with a fin on the lower side only. 



c. Himantura. — Tail without any fin. 



2. Pteroplatea, Mull. & Henle. — The Sting Rays with the body 

 broader than long ; the tail shorter than the body ; the teeth termi- 

 nating in one or three points. 



3. Tasniura, Mull. & Henle. — Tail with no upper fin ; lower one 

 extending to the tip ; teeth pointed, with an elliptical base ; mouth 

 undulated; the projecting part of the upper-jaw forms a sharp edge 

 on each side. 



4. Hypolophus, Miill. & Henle. — Tail very high, with lower fin 

 not reaching to the tip ; teeth hexagonal, very small in the middle 

 of the upper-jaw, and large on the sides. 



5. Urolopkus. — Tail with a fin at the tip; teeth as in Raja, bear- 

 ing in the middle a wreath or point. 



