BRITISH STALK-EYED CRUSTACEA. 229 



in the male and seven-jointed in the female, and in both fringed 

 with setse. Its colour is white, with a faint greenish tinge ; but 

 specimens are not unfrequently found of a delicate pink suffused 

 over the whole of the carapace, whilst the legs are of the normal 

 white colour. There is often a circular spot of red on each side 

 of the carapace, over the branchial region, which greatly varies in 

 size, and which is quite absent in some specimens. 



According to Bell, this species is only recorded from Galway, 

 where it was first discovered ahout 1857. We have obtained 

 it in somewhat considerable numbers from Jersey, where it 

 is found buried in the sand, being similar in habits to the next 

 species. 



This has been called by Jersey fishermen the "Thumb-nail 

 Crab," the only popular name we ever heard for the species. 



Corystes Cassivelaunus, Leach. 



This species, again the only one of the genus known to inhabit 

 our seas, is popularly known as the "Masked Crab," from the 

 resemblance of the marking of the regions on the carapace to a 

 human face or mask. It is a remarkably interesting species for 

 several reasons, and may be described as follows : — 



The carapace is much longer than broad, somewhat cylin- 

 drical, and approaching in form the carapace of the Macroura. 

 It is about an inch and a half in length and about half that in 

 width, roughly oval in shape, and armed with three spines on 

 each lateral margin. The orbits are large, and the space between 

 them is notched. The antenna? are very long, being nearly as 

 long as the carapace, and slightly plumose. 



The anterior pair of legs are remarkably long in the male, 

 but only about a third as long in the female ; they are rounded 

 in form, and enlarged at the base of the forceps, which are 

 serrated and hairy; the wrist is armed with spines. The 

 remaining legs are somewhat compressed, and slightly fringed 

 with setae on both margins. The abdominal somites are five in 

 number in the male and seven in the female, narrow in the former 

 and, as usual, broader in the latter. 



The ova are small, and resemble that of Carcinus mcenas ; 

 they are exuded in the spring-time, and are a dull yellowish 

 brown, becoming very interesting under the microscope as the 

 formation of the enclosed zosea proceeds. 



