284 
ZOOLOGY OF THE FAR EAST. 
moderately excavate anteriorly ; I have not seen any individual with this segment as 
slender as in de Man's examples from the Nargi River in Flores (de Man, I.e., 1892, 
p. 403, pi. XXV, fig. ^id). The fingers are usually a Uttle longer than the palm. 
In the second peraeopods the carpus is from to li times as long as the chela 
and is from 4 to 4^ times as long as its greatest breadth. 
The usual spines are present on the ischium, merus and carpus of the last three 
peraeopods. The dactylus of the third pair generally bears from 8 to 10 spines, but 
in specimens from the Patani River the number is higher, from 12 to 15. In the fifth 
peraeopods the propodus is from 3f (Tinnevelly) to 4^^ times (Patani R.) the length of 
the dactylus. The latter segment usually bears from 32 to 39 spinules ; but, as in 
the case of the third pair, the number is higher in specimens from the Patani River, 
varying from 45 to 55. 
The outer uropod is provided with from 8 to 11 movable spines. 
Large specimens reach a total length of about 38 mm. 
The size of the eggs is somewhat variable. In specimens from Calcutta, Portu- 
guese India and the Patani River they are from 0 35 to 0 43 mm. in length and from 
0*23 to 0 28 mm. in breadth. In those from Travancore and Tinnevelly they are 
slightly, but noticeably larger, from 0 50 to 0-52 mm. in length and from 032 to 0*33 
mm. in breadth. The lowest of these determinations agrees with de Man's description, 
in which the length is stated to be \ mm. Even between the extremes the variation 
is small, but it is noteworthy that the specimens from Travancore and Tinnevelly 
that possess the largest eggs were found in fresh water, whereas all the rest, including 
those from which de Man drew up his description, were obtained in places within 
the reach of tidal influence. 
Summarizing the foregoing observations it may be stated that material from five 
distinct regions (four situated in the Indian Peninsula and one in Siam) shows 
little signs of local variation. Three points only call for emphasis, — (i) in specimens 
from the Tinnevelly district in S. India the average number of upper rostral teeth is 
below normal, (ii) in specimens from Lower Siam the number of spines on the 
dactyli of the last three legs is above normal, and (iii) specimens from water that is 
brackish or subject to tidal influence have smaller eggs than those obtained in 
fresh water. 
The colouration of living specimens is distinctive. The animal as a whole is 
translucent with the rostrum, the lower surface of the last abdominal somite, the 
distal two- thirds of the telson and frequently the tips of the uropods deeply pigmented. 
The carapace is without markings, but there is a short transverse row of chromato- 
phores on the third abdominal somite and a longitudinal line of similar chromato- 
phores near the inferior margin of the first five somites. The depth of pigmentation 
is variable. In extreme cases the whole of the rostrum, the antennules, the inner edge 
of the antennal scale and the tail-fan are deeply pigmented and there is a broad lateral . 
longitudinal band on either side of the abdomen. 
In my experience C.gracilirostris is a scarce form, much less abundant than other 
species of the same genus with which it is found associated. 
