Chap. IX. 
CRUSTACEANS. 
335 
threw some shells towards the hole. One rolled in, 
and three other shells remained within a few inches of 
the mouth. In about five minutes the crab brought 
out the shell which had fallen in, and carried it away 
to the distance of a foot ; it then saw the three other 
shells lying near, and evidently thinking that they 
might likewise roll in, carried them to the spot where 
it had laid the first. It would, I think, be difficult to 
distinguish this act from one performed by man by the 
aid of reason. 
With respect to colour which so often differs in the 
two sexes of animals belonging to the higher classes, 
Mr. Spence Bate does not know of any well-marked 
instances with our British crustaceans. In some cases, 
however, the male and female differ slightly in tint, 
but Mr. Bate thinks not more than may be accounted 
for by their different habits of life, such as by the 
male wandering more about and being thus more ex- 
posed to the light. In a curious Bornean crab, which 
inhabits sponges, Mr. Bate could always distinguish the 
sexes by the male not having the epidermis so much 
rubbed off. Dr. Power tried to distinguish by colour 
the sexes of the species which inhabit the Mauritius, but 
always failed, except with one species of Squilla, pro- 
bably the S. stylifera , the male of which is described as 
being “ of a beautiful blueish-green,” with some of the 
appendages cherry-red, whilst the female is clouded 
with brown and grey, “with the red about her much 
“ less vivid than in the male .” 10 In this case, we may 
suspect the agency of sexual selection. With Sa- 
phirina (an oceanic genus of Entomostraca, and there- 
fore low in the scale) the males are furnished with 
10 Mr. Oli. Fraser, in ‘Proc. Zoolog. Soc.’ 1869, p. 3. I am indebted 
to Mr. Bate for the statement from Dr. Power. 
