Crustaceans. 41 



abdomen, popularlj' but erroneously regarded as the tail, is 

 reduced in length, without expanded tail-flap, and permanently 

 flexed, while the appendages of this region of the body are 

 considerably modified. The most common with us is the shore 

 crab {Carciniis incenas), and it is also the most conspicuous as it 

 has the power of remaining for a considerable time out of water 

 and is seen running at low tide on the sand or on the mud-flats 

 of estuaries. It is dark green above, reddish below in adult 

 specimens, green, mottled with white and black, in the young. 

 The carapace, or shield protecting the body, is slightly broader 

 than long, with the margin deeply toothed in front. ]\Iuch 

 eaten by the poorer people on the coast, it does not often find its 

 way to the London market. The edible crab (Cancer pagitrns) is 

 the most esteemed for the table, occasionally measuring as much 

 as eleven inches in width, and weighing up to twelve pormds 

 (Fig. 41). The carapace is much broader than long, with smooth 

 anterior margin, pale reddish-brown above, sometimes with a 

 purplish tinge, and the big claws are tipped with black. The 

 edifjle crab is far more aquatic than the shore crab, and soon 

 dies when removed from the water. The adults are onl}/ found 

 at some distance from the shore, but young specimens are 

 occasionally met with nestling under stones nr rock-pools. 

 In such situations we may come across another crab which 

 bears a strong resemblance to the shore crab in the shape of 

 the carapace — the swimming crab {Portunus fiiher), readily 

 distinguished by the shape of the last pair of legs, with the 

 terminal joints flattened and paddle-shaped, for the purpose 

 of swimming and digging in the sand. 



In the three species considered so far the carapace is broad 

 and truncate in front. In the spider crabs it is almost triangular, 

 tapering anteriorly into a prominent rostrum. The spin)- 

 spider crab (Maia squinado) is commonly found in shallow 

 water about tidal rocks. Next to the edible crab it is the largest 

 of the British Brachyura, reaching a length of eight inches. > 

 The carapace is studded with spines and the rostrum is forked.'' 

 This crab is usually overgrown with seaweeds and zoophytes, . 

 which render it highly inconspicuous in its natural surround- 

 ings (Fig. 42). This growth is not entirely due to the sluggish 

 habits of the crab, as formerly believed ; it has been observed 

 to dehberately insert the weeds on its dorsal surface, to the 

 rugosities of which they readily adhere. The spiny spider-crab 

 (Fig. 43) is only eaten by the poorer classes in England, but it 

 finds a ready sale on the markets in the North of France. Several 

 other spider-crabs occur more or less frequently on our coasts. 



