12 THE ZOOLOGIST. 



Carcinus mcenas, Leach. 



Again we have an instance of a genus represented by a single 

 species, which is the commonest British crab. It is popularly 

 known as " The Shore Crab," which is so commonly met with in 

 our sea-side rambles. Although so extremely plentiful, it is not, 

 on account of its small size, much used as an article of food, 

 except in some districts by the poorer classes, although its flavour 

 is decidedly sweet and pleasant. It is not unusual, however, to 

 see barrows laden with this species hawked by costermongers at 

 the east end of London. 



The carapace of Carcinus mcenas is slightly convex, regularly 

 denticulated on the anterior margin, which is an even curve. 

 The lateral margins converge towards the posterior margin at an 

 angle of about 45°. The posterior margin is quite straight, with 

 an elevated waved margin, when viewed vertically. The anterior 

 pair of feet are of moderate size, the wrist toothed and the 

 pincers denticulated. 



The chelae are of great service to the owner, for no other 

 crab has such pugilistic and predatory habits as Carcinus mcenas. 

 If driven to defend itself, it will fiercely attack with these by no 

 means insignificant weapons. If, however, it can burrow in the 

 sand or mud of the shore it will do so, leaving its eyes, antennae, 

 and anterior legs uncovered. In this position few of its enemies 

 will dare to attack it. The remaining legs are somewhat simple and 

 smooth, the fifth pair having a few hairs on their lower margin. 



The abdominal somites are five in number in the male and 

 seven in the female, the latter being, as usual, broad and adapted 

 to cover a large mass of ova. 



In the case of this crustacean the ova are not of so brilliant a 

 colour as are those of many other species, being of a dull yellowish 

 brown tint. They are not fixed in such definite groups either, as 

 many of those we have referred to, but are arranged in rows 

 attached to a common centre, each ovum being attached to a 

 main ligature by an equal-sized stem. This arrangement is 

 dissimilar to the usual method on which the ova of the Brachyura 

 are attached. The eggs are exuded at intervals extending over a 

 long period. We have obtained the female with spawn from spring 

 to autumn, but consider that this is due, to a great extent, to the 

 more or less favourable conditions under which the animal exists. 



