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 live 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. stijlifera, 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. Oh. Fraser, in 'Proc. Zoolog. Soc.' 1869, p. 3. I am indebted 

 to Mr. Bate for the statement from Dr. Power. 



