R. DOUGLAS LAURIE—BRACHYURA. 449 
6 mm., variability is practically nil, whereas variability is high in crabs with 
C.1. from 9 to 11 mm. 
The spiniform character of the tooth on the anterior edge of the arm gives 
place to the tubercular condition in crabs whose C.1. has reached about 9 mm. 
The spiniform armature of the posterior edge of the arm becomes granular 
when the C.]. reaches about 6 mm. 
Another point to be noted is that ovigerous females occur with C.l. of only 
6 mm. and that the different conditions of the characters above described are 
thus related with size rather than with sexual maturity ; this is quite usual 
among crabs. On the other hand, the same ovigerous specimens have the 
broadened form of abdomen, an example of a character associated with sexual 
maturity rather than with size. 
The number of individuals in which the right or left hand respectively is 
the larger is approximately equal, thus the right is larger in 19 and left 
in 21 individuals. 
Some notes on the high variability of this species are given by A. Milne- 
Edwards (1873 (1), p. 214). 
42a, CHLORODIELLA NIGER, var. CYTHEREA (Dana, 1852). See Dana, 1852, 
pela, pla lifes. 2 are: 
Chlorodius cytherea, Dana, loc. cit. 
Chlorodius cytherea, Stimpson, 1907, p. 50. 
Localities. Station V. G, 1 g juv. [167], 5 2 juv. [168-172]; Station 
IX. A, 4 g [173-176], 2 9 ovig. [177, 178]. 
Remarks. C. 1. ranges in the @ specimens from 2 to 4°5 mm. and in the 
3 from 3 to 5°25 mm. In the largest ¢ (176) C.b. is 8°25 mm. and C.b.+ 
Ole De 
The length of the larger cheliped is related to the carapace length as 
follows :— 
177 2 ovig. 178 Q ovig. SUS ee LAN Syne welch Ore 
Gil piegemonc es 4-0 45 4:0 4°75 5:0 5°25 mm. 
(O)nA Ra eae nange 775 8°75 8-0 9°75 12:0 11:25 mm. 
Chi.+C.l. .... 1:94 1:94 2-00 2°05 2-40 2°10 
Larger Ch, .... Right Right Left Left Right Left 
C. cytherea (Dana) is included by Alcock (Alcock, 1898, p. 160) as a 
synonym of C. niger. It appears possible that it may come to be re-elevated 
to specific rank, but I have not sufficient data to warrant my taking this 
step. ; 
Var. cytherea has not hitherto been recorded from the Red Sea. 
LINN. JOURN.—ZOOLOGY, VOL. XXXI. 35 
