Crustaceans. 39 



The Crawfish (Palinurus vulgaris) differs chiefly from the 

 Lobster in having no large pincer-claws. It is not uncommon 

 in the Western parts of the Cliannel, but becomes rare in the 

 North. The swimming forms com^prise the equally familiar 

 creatures divided by the fishmonger into shrimps and prawns, 

 according to size, a classification which, however convenient 

 it may be for trade purposes, is wthout meaning to the naturalist, 

 who distinguishes many species irrespective of size. The true 

 shrimp (Crangon vulgaris) is easily recognised by the slightly 

 flattened carapace and the small size of the prow or rostrum, 

 here reduced to a minimum (Fig. 39). The first walking-leg ends 

 in a comparatively large pair of pincers of a peculiar type, the last 

 joint folding back over the penultimate like the blade of a pen- 

 knife. One of the most abundant of the coast species, it is 

 found with us wherever there is a plentiful supply of fine sand. 

 When alive, it is of a speckled grey colour, harmonising with 

 its surroundings ; boiled, it is of a reddish-brown tint — the 

 brown shrimp of commerce. In size it rarely exceeds two 

 inches and a-half . The majority of the other edible forms of this 

 division fall into two genera, Pandalus and Leander {Palcemon), 

 and, according to their size, are sold as shrimps or prawns ; 

 of a bright pink when boiled, tlie smaller specimens of these 

 genera are called pink shrimps. They further differ from the 

 bro^vn shrimps in having the carapace rounded, not depressed, 

 and in being provided with a long, saw-like rostrum. The 

 largest British pra^¥ns belong to the genus Leander and attain 



FIG. 39. SHRIMP (crangon VULGARIS). 



a length of four and a half inclies. In this genus the first two 

 pairs of walking-legs have pincers of the ordinary type. The 

 various species frequent rocky parts of the coast, and small 

 specimens are found in abundance in rock-pools. L. serraius, 

 the commonest species, is grey, spotted and banded with dark 

 purplish brown (Fig. 40). 



