Chap. X.] 



THE THERAPOK 



337 



in their internal organisation that they differ most from 

 the perches of Europe ; their skeletons are composed of 



THE tlAPON QUADRILINEATUS. 



fewer vertebrae, and the air bladder of the Therapon is 

 divided into two portions, as in the carps. Four species 

 at least of this genus inhabit the lakes and rivers of 

 Ceylon, and one of them, of which a figure is given above, 

 has been but imperfectly described in any ichthyo- 

 logical work 1 ; it attains to the length of seven inches. 



In addition to marine eels, in which the Indian coasts 

 abound, Ceylon has some true fresh-water eels, which 

 never enter the sea. These are known to the natives 

 under the name of Theliya, and to naturalists by that of 

 Mastacembelus. They have sometimes in ichthyological 

 systems been referred to the Scombri dse and other ma- 

 rine families, from the circumstance that the dorsal fin 

 anteriorly is composed of spines. But, in addition to the 



1 Holocentrus quadrilineatus, in the spinous dorsal fin. There 



Block. It is allied to Helotes are two specimens in the British 



polytoenia, Bleek., from Halma- Museum collection, one of which 



heira, from which it can be has recently arrived from Amoy ; 



readily distinguished by having of the other the locality is un- 



only five or six blackish longitu- known. See Gunther, Acanthopt. 



dinal bands, the black humeral Fishes, vol. i. p. 282, where mention 



spot being between the first and of the black humeral spot has been 



second ; another blackish blotch is omitted. 



Z 



