84 
HISTORY OF BRITISH CRUSTACEA. 
numbers compensate for its small size. The Rev. Alfred 
Norman remarked, that the southern specimens are smaller 
and paler in colour than those he took in the Clyde, under 
stones at extreme low water. Mr. Couch ^ has described a 
minute Vorcellana found by him in Cornwall on a coralline 
from deep water; he has named it P. acantJiocheles . He 
says that “ on the ridge of the second section of the hand- 
legs there are two well-marked spines. The carapace in 
front is divided into three scarcely separated portions.” 
This seems to be only a young specimen of P. longicornis . 
Suborder III. Macroura, Latr. 
This suborder, of which the Lobster is a well-marked ex- 
ample, is distinguished by the great development of the 
abdomen, which is generally extended and longer than the 
carapace ; the seven rings of which it is composed are all 
movable, and the first five have generally each a pair of 
false feet, with two terminal plates finely ciliated on the 
edges, and which act as oars when they swim. The abdo- 
men is furnished at the end with a large swimming tail 
formed of five plates arranged like a fan. 
* Cornish Fauna, p. 76. 
