OEUSTACEA. 471 



Corystes Dentatus. — Milne Edwards, Sist. des Crust., vol. 2, p. 

 148 ; Coach, Cornish Fauna, p. 74. 



Cancer Cassivilamis — Pennant, pi. 7. C. Personatus, of some 

 writers. 



It is commoB. on sandy shores at low water, 'Vtere it burrows 

 in the sand, leaving the extremities of the antennae alone projec- 

 ting above the surface. These organs are of some use beyond their 

 common office of feelers, perhaps as in some others, they assist 

 in the process of excavation ; and when soiled by labour, I have 

 seen the Crab effect their cleaning by alternately bending the 

 joints of these stalks, which stand conveniently angular for this 

 purpose. Each of the long antennae is thus drawn along the 

 brush that fringes the internal face of the other, until both are 

 cleared of every particle that adhered to them." 



The animal received its synonym of Masked Crab from the 

 representation of a human face impressed upon its carapace. 



ANOMUEA.— (Soft-tailed Crabs.) 



The genera of this group are distinguished from the Brachyura 

 by the length of the pleon or tail, many of which from occupying 

 shells of molluscs and other situations have no hard or crus- 

 taceous covering, hence their name. But the whole group or 

 sub-order are recognized by having the fifth and sometimes the 

 fourth pair of legs feeble and small. 



PAGURIB^. 



Genus, Pagtjrtjs. 



"The abdomen (pleon) large and membranous, turned side- 

 ways ; the pairs of the abdominal feelers irregular." 



Pagtjeus bernhabdus. — Limi. ; Milne Edwards, Sist. des. Crust, 

 t. ij, p. 215; Bell, Brit. Stalh-eyed Crust., p. 171. 



P. Streblonyx — Leach, Malac. Brit. p. 26 ; Pennant, pi. 17. 



' ' Common and abundant, the smaller in pools left by the tide, 

 the larger in a considerable depth of water ; where they become 

 so large as to occupy AVhelk shells {Buccimim) of the largest size. 

 As Crabs of this genus are weak and "defenceless in the hinder 

 parts of the body, they exercise the well known habit of residing 



