Proceedings. 97 



breakers hurl the granite pebbles wildly about, we have 

 Xantho flonda, a stoutly built crustacean that might almost 

 be stepped upon without injury. Its home is in the rocky 

 crannies, where it lives quietly with its less common co- 

 species, Xantho rivulosa. 



Another (jurious form is Corystes Cassivelaunus, or Masked 

 Crab, the gastric impression on its thorax somewhat re- 

 sembling a human face, though certainly a grotesque one. 

 This crustacean possesses long pectinated antennae, much 

 resembling some of the Lepidoptera in this respect. Its 

 habits are interesting ; it burrows in the sand at the bottom 

 of shallow water, leaving its eyes and antennae exposed, and 

 pounces out upon its prey as it happens to come near it, 



Gonoplax angulata and Atelecyclus heterodon are deejj-water 

 species, and moreover rare, so that their life-history is but 

 little known ; but Planes linnceana, though included as British, 

 is an illustration of geographical distribution by means of 

 ocean currents and floating bodies. It is essentially a sur- 

 face or floating species, and finds its way to our southern or 

 western shores on fragments of wreck or such water-logged 

 material ; though it is evidently a tropical, or at any rate a 

 Mediterranean, form. The little Pea Crabs, Pinnotheres pisum 

 and P. veterum, are usually found in the shells of living 

 Mollusca, the former in that of the Oyster and the latter in 

 that of the large Pinna manna. 



We wiU now glance at the intermediate tribe, the Anomoura, 

 which I have already said embraces both Lobsters and Crabs, 

 but which have the fifth pair of legs rudimentary. The 

 Hermits are an amusing family, for to watch the pranks of 

 the common one, Pagurus Bernhardns, in a tank is really quite 

 ludicrous ; but they are, moreover, exceedingly interesting. 

 P. Bernhardus, though inhabiting the dead shells of several 

 species of MoUusca, seems to affect chiefly that of the common 

 Whelk (Buccinuyn undatum), whilst P. Prideauxii is almost 

 invariably found in that of Trochus magus, a shell certainly 

 not large enough for its proper protection ; and so we finiiit 

 always in company with an Anemone, Adamsia palliata, 

 which seems to afford the Hermit Crab additional cover, so 



H 



