CRABS. 251 



tion. The black mud along the coast 01 Borneo assumes quite 

 a brilliant blue tinge, when, at low watei, during the heat of 

 the day, the coerulean Gelasimi 

 come forth to feed. 



The Venetian lagoons also har- 

 bour a vast number of the common 

 Shore-Crab (Portunus Mcenas), 

 the catching of which affords a 

 profitable employment to the in- cauing-crab of Oeyion. 



habitants of those swampy regions. 



Whole cargoes are sent to Istria, where they are used as bait for 

 anchovies. The fishermen gather them a short time before they 

 cast their shell, and preserve them in baskets, until the moulting 

 process has been effected, when they are reckoned a delicacy even 

 on the best tables. On attempting to seize this crab, it runs 

 rapidly sideways, and conceals itself in the mud; but when un- 

 successful, it raises itself with a menacing mien, beats its claws 

 noisily together, as if in defiance of the enemy, and prepares for 

 a valiant defence, like a true knight. 



The most valuable short-tailed crustacean of the North Sea is 

 undoubtedly the Great Crab (Cancer pagurus), which attains 

 a weight of from four to five pounds, and is consumed by 

 thousands in the summer, when it is in season and heaviest. 

 It is caught in wicker-baskets, arranged so as to permit an easy 

 entrance, while egress is not to be thought of. 



The legs of the crabs are very differently formed in various 

 species. In those which have been called sea-spiders they are 

 very long, thin, and weak, so that the animal swims badly, and is 

 a slow and uncertain pedestrian. For greater security it therefore 

 generally seeks a greater depth, where, concealed among the sea- 

 weeds, it wages war with annelides, planarias, and small mollusks 

 Sea-spiders are often found on the oyster-banks, and considered 

 injurious by the fishermen, who unmercifully destroy them 

 whenever they get hold of them. 



In other species the legs are short, muscular, and powerful, 

 so as rapidly to carry along the comparatively light body. The 

 tropical land-crabs and the genera Ocypoda and Grapsus, which 

 form the link between the former and the real sea-crabs, are 

 particularly distinguished in this respect. 



The Rider or Raner (Ocypoda cursor), who is found on the 



