r910.} J. R. HENDERSON & G. Mattuai: Freshwater Prawns. 205 
Localities.—A large number of males and females from Madras: 
several males from Cocanada. 
General distribution.—P. rudis has been recorded from Mada- 
gascar (Coutiére), Mozambique (Hilgendorf), East Africa (Pfeffer) , 
and Ceylon (Heller). 
PALAEMON NOBILII, n. sp. 
(Pl. xvii, figs. 6a—e.) 
We include in this species two specimens from Walajabad, 
Chingleput District, a male and a female, the latter bearing eggs, 
which differ greatly from all the other Indian species which we 
have examined. 
Characters of the male.—The single specimen measuring 
64 mm. in total length is well developed and apparently possesses 
adult characters. The rostrum tapers somewhat abruptly towards 
the acute tip, and extends slightly in front of the antennular stalk ; 
the dental formula is a The part of the upper rostral margin 
on which the fourth to the tenth teeth are situated is convex, and 
the apex forms an acute slightly upturned tooth. ‘The first five 
upper teeth are on the carapace, and of these the first four are 
separated by wider intervals than the others; the last tooth is 
placed a little distance from the apex. 
The large chelipedes are sub-cylindrical, and unequal, the left 
one longer than the right. In the former, the palm is slightly 
compressed dorso-ventrally, and is as wide as the distal end of 
the carpus; the finger-tips are abruptly incurved. The distal 
tooth on the mobile finger is a little behind the middle of the joint, 
and is smaller than the proximal tooth; the tooth on the immo- 
bile finger is about the same size as the distal tooth on the mobile 
finger. The chelipedes are provided with numerous forwardly 
directed spinules ; those on the under surface being fewer but more 
strongly developed than those on the upper surface. The teeth 
on the median ridges of the fingers of the short chelipede are 
weaker, and the opposed margins are provided with more numerous 
setee; in other respects the short chelipede is similar to the longer 
one. The joint-measurements are as follows :— 
Total length i m. c: py fe 
R. chelipede .. 56 85 II 145 15 7 
J. chielipede «.... 70°75 10°75 E3°75,,, LO) Usi75 | S 
It should be noticed from the above measurements, that the 
fingers are shorter than half the length of the palm, and that in 
the longer chelipede, the carpus is much longer than the merus. 
The telson-tip is not so acute as in P. carconus and P. mal- 
colmsonii; the inner lateral spinules extend beyond the tip by a 
little less than half their length; the outer spinules are very short; 
