63 A HISTOEY OF EECENT CEUSTACEA 



they are beyond the reach of the breakers.' ' The lady- 

 crab is predacious in its habits, feeding upon various 

 smaller creatures, but like most of the crabs it is also 

 fond of dead fishes or any other dead animals. In some 

 localities they are so abundant that a dead fish or shark 

 will in a short time be completely covered with them, but 

 if a person should approach they will all suddenly slip off 

 backwards and quickly disappear in every direction be- 

 neath the sand ; after a short time, if everything be quiet, 

 immense numbers of eyes and antennae will be gradually 

 and cautiously protruded from beneath the sand, and after 

 their owners have satisfied themselves that all is well, the 

 army of crabs will soon appear above the sand again, and 

 continue their operations. The colour of this crab is quite 

 bright, and does not imitate the sand, probably owing to 

 its mode of concealment. The ground-colour is white, but 

 the back is covered with annular spots formed by specks 

 of red and purple. It is devoured in great numbers by 

 many of the larger fishes.' 



Polybius, Leach, 1820, is closely related to the three 

 preceding genera, and like the last has the capacity for 

 swimming highly developed. The single species, Polyhim 

 Henslowii, Leach, is European, and is distinguished by 

 having much compressed joints not only in the last pair 

 of legs, but also in the three preceding pairs. It is said 

 to pursue fishes so active as the mackerel, to fasten upon 

 them with its sharp pincers, and to hold on till they 

 succumb. The fishermen in consequence call it the 

 nipper crab. Probably it is only fish that are terrified or 

 hampered by the proximity of the fishing-net that fall vic- 

 tims to its agility. The Prince of Monaco records that on 

 one occasion, off the coast of Spain, his bursting trawl-net 

 brought up from a considerable depth at a single haul about 

 five thousand fine specimens, which produced an animated 

 scene on board his yacht by nimbly fastening with their 

 cat-like talons on to the bare toes and fingers of the crew. 



Scylla, de Haan, 1833, belongs to a group of genera 

 in which the carapace is very broad, and the antero-lateral 

 margins are armed with nine or more teeth. Some of the 



