TORPEDO. 125 



the dorsal fins are almost always upon the tail, which is very 

 slender. This group is divided into Rays properly so called, 

 Tofpidoe*, &c. 



17. The Rays properly so called-, Raia, have the body of a 

 rhomboidal form, a slender tail, fine teeth, &c. Our coast fur- 

 nishes many species, such as the Skate, Sting- Ray, &c. 



18. The TORPEDOES, or ELECTRIC RAYS, Torpedo, have a 

 short, but fleshy tail. The body is smooth and in form of a 

 nearly circular disk, the anterior border of which is- formed by 

 two prolongations of the snout, which, on each side go to join 

 the pectoral tins, and leave between these p- Q^ 

 organs, and the head and branchiae, an oval ' 

 space ( Fig. 64.) in wnich is lodged the ' ' a 

 electric apparatus of these fishes. This appa- 



ratus consists of a multitude of vertical, mem- 

 branous tubes, placed close together like the 

 cells of a honey-comb, subdivided by hori- 

 zontal partitions into small cells filled with 

 mucus, and supplied by numerous large 

 branches of the pneumogastric nerve. In these 

 singular organs is produced the electricity, by 

 aid of which torpedoes communicate electric 

 shocks to those who touch them, a faculty 

 possessed by the malapteruri, (Page 103.) and TORPEDO^ 

 gymnoti,(f7ell5.)but which, in these last, is seattJ in a different 

 structure. These fishes are less powerful than the gymnoti, but 

 can nevertheless, benumb the arm of a person touching one of 

 them, and they probably resort to this means to obtain their 

 prey. Several species are found on the coasts of France. 



ORDER OF CYCLOSTOMT. 



19. This last order of cartilaginous fishes is characterised by 

 the singular conformation of the mouth, and is composed of the 

 most imperfectly organised of all the vertebrate animals. 



20. Their body, elongated, naked and viscid, is unprovided 

 with thoracic and abdominal extremities ; for both the pectoral 



* Explanation of Fig, 64. The Torpedo, or Electric Ray: a. a portion 

 of the skin detached to show one of the electric organs, (6.) 



17. What are the characters of Rays properly so called? 



18. How are the Torpedoes characterised ? What is the nature of theii 

 Wectric apparatus ? 



19. How is the order of Cyclostomi characterised ? 



20. What are the characters of fishes of this order? What are thn pecu 

 liarities of their respiratory apparatus ? 



10* 



