THE STALK-EYED CRUSTACEA, 253 



Pisa tetvaodon occurs at the Nore and may be considered an 

 Essex species. 



Another interesting family are the Swimming Crabs or 

 Portunidas. They have the fifth pair of legs terminating in 

 paddles, and although they do not really " swim " in the proper 

 sense of the word, they possess the power of raising themselves 

 from the sea bottom, and making short aquatic flights. An 

 exception to this, however, is presented in the case of Polybius 

 henslozmi, which has an exceedingly thin chitinous carapace. 

 This species has often been taken in herring-nets, a fact which 

 proves that it must be a hardy swimmer, as its structure would 

 lead one to expect. An exceedingly delicate member of this 

 family is Portnmniis latipes, a rather rare species near our coasts, 

 but much more abundant on the French side of the Channel. 



PovUtmmis piihcy, the " Lady Crab " of the Channel Islands, is 

 a handsomely marked species : unhappily the bright colours 

 disappear at death, so that no idea of its beauty can be formed 

 from a dried specimen. 



The Common Shore-Crab {Cavcinus mwnns) is very widel\' 

 distributed and is a well-known Essex form, where its colour is 

 invariably identical with the sandy or muddy bottom on which 

 the creature lives. When, however, we find it in rock-pools on 

 the granite or serpentine of Cornwall, or on the syenite or 

 basaltic shores of the Channel Islands, this interesting species 

 assumes the most beautiful markings, tinted with really gorgeous 

 colour, and mottled in the most delicate manner. It is often 

 almost impossible to detect the Crab in these localities, so per- 

 fectly does it resemble its surroundings. 



The (^enns Xantho [X.Jlovida and A', rivulosa) has its carapace 

 very solid and strongly built up. It is found in the wildest rocky 

 shores of the Channel Islands where the waves break, and where 

 a more slender form could not hojd its own. I ha\e stood upon 

 a specimen of Xantho flovida without crushing it. 



Porcellana platychcles is a ver}- small species, somewhat 

 dull and dirty in colour, and I have always found it on rocks 

 much grown o\er with algae, &c. Whilst P. longicornis, a 

 smooth, pink-coloured species, I have found upon smooth granite 

 boulders. Both these species have a wide distribution. 



Pirimula denticulata is a small interesting species, and is 

 considered to be very rare. When collecting in Jersey, I 



