76 A HISTORY OF RECENT CRUSTACEA 



in 1833 over Nautilocorystes instituted by Milne-Edwards 

 in 1837, yet Dicera must give way, having been already 

 earlier used in other classes of zoology ; and secondly, that 

 Oeidia, de Haan, 1833, a name meaning egg-like, must 

 likewise be cancelled, having been found to be a synonym 

 of Gomeza, Gray, 1831, a Corystid genus of the Japanese 

 fauna. 



Legion 4. ThelpJmsinea. 



The carapace is more or less dilated at the branchial 

 regions; the third maxillipeds have the fifth joint articu- 

 lated at or near the front inner angle of the fourth or at 

 its apex. The fingers of the walking legs are usually 

 spinuliferous ; the verges of the male pass directly 

 through the basal joint of the fifth pair. 



The species are fluviatile or live in damp forests. 



Family Thelplmsidce. 



This being the only family has the characters of the 

 legion. Thelphusa, Latreille, 1819, contains numerous 

 species, of which Mr. Miers observes that ' one, the com- 

 mon Tlielpliiisa fluviatilis, occurs not only on the shores of 

 the Mediterranean, but also in Asia Minor, Syria, and 

 Persia ; the others are found in all the warmer temperate 

 and tropical regions of the old world, extending southward 

 to the Cape of Good Hope, Madagascar, and Australia, but 

 not to New Zealand ; a species (TJtelphusa cliilensis) occurs in 

 Chili.' Potamonautes, Macleay, and Geothelphusa, Stimpson, 

 are so closely related to Thelphusa that their separation 

 from it remains a matter of doubtful expedience. 



Krauss remarks that the Thelphusidas are especially 

 fond of clear running streams in which they shelter them- 

 selves under stones and plants. They are easily scared, 

 and in spite of their monstrous chelipeds their long pe- 

 raeopods carry them off at a great pace. The pearly 

 Thelphusa (Thelphusa perlata, Milne-Edwards) has an 

 earthy greenish colour, which matches its surroundings 

 in the rivulets, whereas Thelphusa depressa, a species 



