516 THE OCEAN WORLD. 
elongated claw, which is straight-pointed and channeled longitudi- 
nally : the carapace oblong-oval, terminating in a rostrum anteriorly 
truncated and bordered posteriorly ; the regions are but slightly 
indicated, with the exception of the caudal region, the branchial or 
thoracic regions being very much elongated. 
Latreille gives the name of Corystes-—which sane a warrior 
armed—to this genus of short-tailed Decapod Crustacean, from xdépus, 
a helmet. Pennant had already conferred the name of Cassivelaunus, 
the chief of the ancient Britons, for the singular reason, according 
to Gosse, that the carapace, which is marked by wrinkles, bears, in 
old males especially, the strongest and most ludicrous resemblance 
to the face of an ancient man, but surely Pennant’s well-known sym- 
pathy with his British ancestry certainly never led him to caricature the 
grand old British warrior, as Mr. Gosse surmises. On the contrary, 
he saw in this Crustacean a creature armed at all points, and he’ 
named it after the hero of his imagination. , 
In this species the surface of the carapace is somewhat granulous, 
with two denticles between the eyes, and three sharp points directed 
forward on each side. The male has only five abdominal segments, 
but the vestiges of the separation of two others may be clearly re- 
marked upon the outer mediate or third piece, which is the largest of 
all. The length of the antennz is remarked on by Mr. Couch, in 
his ‘Cornish Fauna.” “These organs,” he says, “are of some use 
beyond their common office of feelers; perhaps, as in some other 
Crustaceans, they assist in the process of excavation; and when 
soiled by labour, I have seen the crab effect their cleaning by alter- 
nately bending the joints of their stalks, which stand conveniently 
angular for the purpose. Each of the long antennz is thus drawn 
along the brush that fringes the internal face of the other, until both 
are cleared of every particle that adhered to them.” On the other 
hand, Mr. Gosse suggests that the office of the antenne is to keep a 
passage open for ejecting the deteriorated water after it has bathed, 
and aérated the gills. “I have observed,” he says, ‘that, when kept 
in an aquarium, these crabs are fond of sitting bolt upright, the 
antenne placed close together, and pointing straight upwards from 
the head. This is doubtless the attitude in which the animal sits in 
its burrow, for the tips of the antenne may often be seen just project- 
ing from the sand. When the chosen seat has happened to be so 
close to the glass side of the tank as to bring the antennze within the 
range of a pocket lens, I have minutely investigated these organs 
without disturbing the old warrior in his meditation. I saw on each 
occasion that a strong current of water was continuously pouring up 
