BRITISH STALK-EYED CRUSTACEA. 99 



dredging: thus bearing out the statement made by Mr. Couch, 

 and recorded by Prof. Bell, as to its swimming and deep-sea 

 habits. A number were obtained from Jersey in the autumn of 

 1880 by a correspondent, tbrough the bursting of a sluice or 

 drain near the shore, the large quantity of fresh water, with its im- 

 purities, evidently overwhelming and killing those that were 

 probably seeking shelter in the sand in the neighbourhood. An 

 enormous number of this supposed rare crab were washed ashore 

 at Shoreham after the great storm of January 24th, 1881 ; and the 

 fishermen of St. Ives, Cornwall, to whom it is known as the " Nip- 

 per," state that large quantities, described as " tons in weight," 

 were washed ashore there in 1878 or 1879. On the Devonshire 

 coast it is often taken in the herring and pilchard nets. 



Though considerable numbers have passed through our hands, 

 we have not obtained a specimen with ova, and therefore think 

 it probable that the females retire to deep water during the 

 spawning season. 



Genus Portunus, Fabr. 



This genus embraces more species than any other of the 

 Brachyura, all of which species are popularly known as swimming 

 crabs, from the blade-like development of the last joint of the 

 fifth pair of legs, somewhat similar to that already referred 

 to in Polybius Hensloivii. The carapace of this genus is broader 

 than long, or rather it is true crab shape. It is denticu- 

 lated on the anterior margins ; that portion between the orbits 

 varying considerably in the different species, as also does the 

 colour and many other details to which we shall refer specifically. 

 The antennae are somewhat longer than those of the preceding 

 genus, and the eyes are fixed on short peduncles. The anterior 

 pair of legs are generally nearly equal, ridged longitudinally, and 

 more or less knotted and notched; the wrist is armed with 

 spines, and the forceps are slightly serrated. The abdominal 

 segments resemble those of Polybius Hensloivii, in being five- 

 jointed in the male, and seven-jointed in the female. The general 

 habits of the genus are remarkable ; some species existing in 

 enormous numbers in limited areas, as if attracted by some par- 

 ticular form of food, which they possibly do good service as 

 scavengers in removing ; while others swim about on isolated 

 foraging expeditions, even attacking fish in open water. 



