68 A HISTORY OF RECENT CRUSTACEA 
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 antenne 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, Polybius 
Henslowti, 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 tili 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 
inargins are armed with nine or more teeth. Some of the 
