Chap. X.] • THE THEEAPON. 
337 
in their internal organisation that they differ most from 
the perches of Europe ; their skeletons are composed of 
THEKAPON QUADRILINEATUS. 
fewer vertebras, 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 das 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 
polytcenia, Bleek., from Halma- Museum collection, one of which 
heira, frorn 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 Gunthek, Aeanthopt. 
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 
