INTRODUCTION. 
13 
of the bottom. It is, perhaps, at this period of repose that 
the crops of seaweeds and corallines fix themselves, as they 
are often seen beautifully adorning them; shells of different 
species, but especially Oysters and Mussels, are also found 
adhering, and on the smaller kinds, as of InacJius and Visa, 
sponge will grow so luxuriantly as to conceal the whole ca- 
rapace, with tufts on the legs to the extremities.” 
These long-legged Crabs are frequently covered with sea- 
weeds, sponges, and other marine productions, which so com- 
pletely change their appearance as to render them no longer 
recognizable. In this way Macropodia occidentalis (Guil- 
ding, Linn. Trans, xiv. 335) disfigures itself in the West 
Indian Seas, and watches for its prey. The British Spider 
Crabs ( InacJius and Arctopsis) are often completely covered 
with masses of algse, the roots of which take a secure hold 
amongst the hairs that clothe the carapace and limbs (Bellas 
Brit. Crust, p. 24). Say and Le Sueur fancied that these 
marine productions w T ere merely entangled mechanically, - * 
but there can be no doubt that they grow and flourish on 
their strange locality. 
Professor Bell has watched the Arctopsis (Pisa) tetraodon 
waiting for its prey. He remarks that the Crabs of this 
* Journ. Acad. Sc. Phil. vol. i. p. 80. 
