( 16 ) 



rains. These hard-rayed fishes, which are taken in the fresh- 

 waters, mostly belong to the following 18 genera, some of 

 which are marine, others not so: 1, Lates ; 2,Ambassis; 

 3, Corvina ; 4, Mugil ; 5, Equula ; 6, Gobius ; 7, Euctenogo- 

 bius ; 8, Periophthalmus ; 9, Eleotris ; 10, JBadis ; 11, Nandus ; 

 12, Catopra; 13, Anabas ; 14, Poly acanthus ; 15, Tricho- 

 gaster ; 16, Ophiocephalus ; 17, Rhynchobdella ; 18, Masta- 

 cembkis. 



XXVIII. The foregoing 18 genera are divisible into two 



Divisible into purely fresh- distinct claSSCS '. first, thoSG 

 waterandpartiallymarineforms. entirely belong to the fresh-Waters 



(although some of the species of the same genus may have 

 marine representatives) ; secondly, those which are marine, and 

 only ascend rivers for predaceous or breeding purposes. Of 

 the true fresh- water ones (2, as Ambassis Thomassi ; 4, as 

 Mugil cascacia ; 6, as Gobius giuris ; 7, as Euctenogobius 

 striatus ; 8, as Periophthalmus Schlosseri ; 9, as Eleotris 

 nigra ; 10, as Badis dario ; 11, as Nandus marginatus ; 12, as 

 Catopra nandioides ; 13, as Anabas scandens ; 14, as Polya- 

 canthus cupanus ; 15, as Trichogaster fasciatus ; 16, as 

 Ophiocephalus gacliua ; 17, as Rhynchobdella aculeata ; and 

 18, as Hastacemblus armatus) some of these are monoga- 

 mous, as Nos. 13, 14, 15 and 16, and probably also Nos. 6 and 

 7, all of which appear peculiarly adapted for tanks and jhils, 

 as they live in the grass along their edges, where the larger 

 varieties lie in wait for frogs or other animals on which they 

 prey. Whilst the first four named genera being air-breathers 

 (see para. XLIII) they have only to raise their mouths out of 

 the water and take in their modicum of air. Others of these 

 fresh-water genera are apparently polygamous, as Nos. 2, 10, 

 11, 12, 17 and 18. Of those genera which possess marine repre- 

 sentatives, some of which breed in the sea, whilst others ascend 

 rivers for this purpose, are Nos. 4, 5, 6, 7, 8 and 9. But some of 

 these genera placed as polygamous, as the gobies, may even- 

 tually prove to be monogamous. Of the whole of these 

 Acanthopterygians but few are generally distributed through 

 the inland tanks far from the sea level or beds of large rivers ; 

 these exceptions are the little Ambassis ; a goby, Gobius giuris ; 

 the small Badis and percoid Nandus ; the walking fishes, 

 Opliiocephalus, and the spined eels, namely, the Rhynchobdella 

 and Mastacemblus. Of the second or marine division of this 

 order of fishes, some (1, as Lates calcarlfer ; 3, as Corvina 

 coilor ; and 5, as Equula,) are marine, ascending rivers at 

 certain seasons, as in the rains, in order to obtain food, 



