1916. | B.SUNDARA Raj: Freshwater Fish of Madras. 291 
APPENDIX. 
REMARKS ON THE GENUS HAPLOCHILUS, 
Tate Regan! has recently suggested a division of the genus 
Haplochilus into two genera, viz. the genus Haplochilus proper, 
represented in India by the single species melanostigma, and the 
genus Panchax, to include the remaining species panchax, lineatum, 
rubrostigma, dayi and parvus. He has stated the differences as fol- 
lows :— 
“In the one (Panchax) the praemaxillaries are flattish and somewhat pro- 
duced, protractile, the cleft of the mouth is rather wide, horizontal, almost semi- 
circular, the teeth are in bands, with an outer and a more or less distinct inner 
series of enlarged teeth, vomerine teeth and pseudobranchiae are present, the 
gill-membranes are not united, and the pectoral fins are placed low. In the 
other (Haplochilus) the mouth is small, transverse, not protractile, with the teeth 
in a single series, sometimes followed by a second series of minute teeth; there 
are no vomerine teeth or pseudobranchiae, the gill-membranes are broadly united, 
and the pectoral fins are placed high.”’ 
This division of the old genus Haplochilus has not been generally 
adopted in India and further research was desired on the sub- 
ject.” At the instance of Dr. Annandale I have recently ex- 
amined all the Indian species save H. rubrostigma and H. dayi* 
of Ceylon, with special reference to the differences between the 
two proposed genera, with the result that I accept Tate Regan’s 
division of the genus but modify some of the differences he has 
pointed out between the two. In addition I have stated other 
differences, notably in the structure of the scales and in the habits 
of the two genera. 
The praemaxilla.—The shape of this bone differs considerably 
in the two genera (pl. xxv, figs. 3, 4 and 5). In Panchax, towards 
the mid-dorsal line of the body where the two premaxillae meet, 
each gives off posteriorly a flat triangular process of considerable 
length: the rest of the bone is narrow, elongate and bent back- 
wards and downwards, tapering to a spine at the extreme corner 
of the mouth. In Haplochilus the triangular process is feebly 
represented by a rounded extension, the rest of the bone is short 
and of uniform breadth, ending in two or more coarse teeth in the 
corner of the mouth, according to the sex. 
The mouth.—The cleft of the mouth in Panchax is wide but 
in Haplochilus it is small: beyond this there is very little to be 
said by way of a difference. If it is semicircular in Panchax, in 
Haplochilus melanostigma too it is so to a slight degree, and as to 
its being horizontal in Panchax and transverse in Haflochilus the 
distinction to a large extent depends on the proportionate lengths 


1 Tate Regan, Ann. Mag. Nat. Hist. (8), VII, p. 324. 
2 Sewell and Chaudhuri, Jnd. Fish of Proved Utility as Mosquito Destroyers, 
te 2s : 
8 Steindachner, Denkscriften der kats. Akad. Wein, LIX, PP. 376-377 
(1892). a 
