Dae BOPYRIDA, 
ISOPODA. BOP YRID. 
NORMALLA. 
Genus—PHRYXUS, RaTuKe. 
(Phryzus and Pleurocrypta, HEsse.) 
Tus genus was instituted by Rathke, for the reception 
of a species of the Bopyride, parasitic on a prawn of the 
genus Hippolyte, remarkable for the very swollen and 
unsymmetrical form of the female, of which the legs on 
one side are nearly abortive in the full-grown state, 
but more especially for the large size of the lobes or 
plate-like branchial appendages of the tail, by which it 
at once differs from the two preceding genera. 
The whole of the species hitherto discovered, including 
three new ones now first made known to the public, are 
parasites on various crustaceous animals belonging to the 
Anomourous and Macrourous divisions, including not 
only the more typical Hippolyte, but also the aberrant 
genera Pagurus and Galathea. 
The male in the species which served for the establish- 
ment of the genus is very minute and elongated in form, 
with the head transversely ovate, with two minute dark 
points indicating the eyes; the upper antenne are very 
minute, and consist of three joints of equal length, but 
gradually becoming more slender to the tip, which is 
furnished with a number of hairs ; the lower antenne are 
much longer, and consist of eight joints, also gradually 
attenuated to the tip. The mouth is transformed into a 
small conical protuberance rising from a semicircular 
Space. The pereion is composed of seven segments 
of nearly equal size, each with the sides rounded and 
wide apart (in specimens distended from having been 
