84 A HISTORY OF RECENT CRUSTACEA 
Since it is during this period of ‘ mouldering’ that the 
crabs are fattest and best flavoured, Herbst finds it easy 
to suppose that greedy man will not leave them safe in 
their repose. On the contrary, he busily digs them out 
with a spade. Considering how readily under some cir- 
cumstances these crustaceans shed their limbs, it is singu- 
lar that in exuviation they are able to cast off their whole 
caparison so uninjured and complete that it might be mis- 
taken for the livinganimal. Careful inspection is required 
to perceive near the insertions of the limbs the ventral slit 
through which the animal has made its escape. 
It was in a West Indian species of Gecarcinus that 
Professor Westwood observed that the young issued from 
the egg in a form not materially different from that of 
their parents, This experience, combined with Rathke’s 
similar observation in regard to the European crayfish, 
led him at first to throw doubt upon Vaughan Thompson’s 
theory of crustacean metamorphoses. But it was soon 
brought to light that the examples of the land-crab and 
the freshwater crayfish were interesting exceptions to a 
still more interesting rule, and there are few who would 
now deny that these exceptions are to be explained as 
modifications in the life-history of the animals concerned, 
acquired late in the course of time to suit the new condi- 
tions of existence encountered by creatures emerging from 
the sea to a life in fresh water or on dry ground. That no 
crustaceans have been able to cut themselves loose from 
some dependence upon moisture is not very wonderful, 
since in that respect man himself is still an aquatic 
animal. 3 
Gecarcinus lagostoma, Milne-Edwards, represented on 
Plate II, is a widely distributed species. 
Hylceocarcinus Humei, Wood-Mason, occurs in ‘the 
dark dense damp forests of the Nicobar Islands.’ 
Uca una (Linn.), the crab of the mangrove swamps of 
Brazil, may be mentioned as a rare instance of one that 
has been allowed to possess the names by which it was 
figured and described centuries ago. In this genus the 
last joints of the walking legs are compressed and un- 
