76 A HISTORY OF RECENT CRUSTACEA 
in 1833 over Nautilocorystes instituted by Milne-Edwards 
in 1837, yet Dicéra must give way, having been already 
earlier used in other classes of zoology ; and secondly, that 
O@idia, 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.—Thelphusinea. 
The carapace is more or less dilated at tke 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 Thelphuside. 
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 Thelphusa 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 (Thelphusa chilensis) 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 Thelphuside 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- 
reopods carry them off at a great pace. The pearly 
Thelphusa (V’helphusa perlata, Milne-Edwards) has an 
earthy greenish colour, which matches its surroundings 
in the rivulets, whereas V'helphusa depressa, a species 
