CHAP. XX] FISHES. 463 



Family 112.— TRYGONID^. (6 Genera, 43 Species.) 



" Eays with the pectoral fins extending to end of snout." 



Distribution. — Seas of all temperate and tropical regions, and 

 rivers of Tropical America. A species of Trygon has occurred 

 on our Southern coast. Ellipesurus and Tceniura are found in 

 the fresh waters of the interior of South America, while the 

 latter genus occurs also in the Indian seas, but not in the 

 Atlantic. 



Family 113.— MYLOBATID^. (5 Genera, 22 Species.) 



" Eays with very broad pectoral fins not extending to end 

 of snout." 



Distribution. — Temperate and tropical seas. A species of 

 Myliobatis is British, but most of the species and genera are 

 confined to tropical seas. Dicerohatis and Ceratoptera are very 

 large Rays, commonly called Sea-devils. 



Sub-class V.— CYCLOSTOMATA. 



" Cartilaginous fishes, with suctorial mouths and without 

 lateral fins." 



Family 114.— PETROMYZONTID^. (4 Genera, 12 Species.) 



" Marine or fresh-water eel-like fishes, with suctorial mouths 

 and without barbels." 



Distribution. — Coasts and fresh waters of temperate legions 

 of both hemispheres. Three species of Petromyzon (Lampreys), 

 are British. 



