122 
GAMMA El DiE. 
are longer than the preceding, and more slender, and 
have the third joints and the wrists not broader than 
the next succeeding joints. 
The segment of the body which carries the ante- 
penultimate pair of caudal appendages is remarkable 
for a notch, deeply cut, near the middle, into its dorsal 
surface. The appendages are shorter than the penulti- 
mate ; the penultimate is shorter than the ultimate ; and 
both have their branches equal. The last pair have but 
one branch, which is much longer than the peduncle, and 
tipped with a strong single spine. The terminal plate is 
double, as in the genus Gammarus , each division being 
subapically tipped with a single spinule. 
The colour of the animal, when taken alive, is of a 
tolerably bright lemon, every segment and joint being 
fringed with a margin of white ; the whole animal is 
thickly covered with minute black spots. The speci- 
mens which have been sent to us, being dead, were 
generally fawn-coloured, tending to a bluish-grey upon 
the back. This constant appearance, together with the 
animal being less compressed than Anonyx and Lysia- 
nassa , enabled us readily to recognize any specimen. 
The first species of this genus was indicated by the 
elder Costa in his “ Catalogue of Nepalese Crustacea,” 
published in 1840, and was subsequently described and 
figured in the “ Fauna del Regno di Napoli, Crust.,” pi. 8, 
fig. 4-7, by his son. The lower antennae are not longer 
than the upper. A second species, C. Hopei , also from 
the Bay of Naples, was described and figured by the 
latter author in the Cf Catalogo dei Crostacei Italiani,” 
published by the Rev. F. W. Hope, Naples, 1851 ; and 
in the te Fauna del Regno di Napoli,” pi. viii. fig. 1. 
The lower antennae in this species are more than half the 
entire length of the animal. 
