4M A HISTORY OF RECENT CRUSTACEA 



Risso's obscure descriptions entitle him to honour or grati- 

 tude. In the present instance, it is said, he mistook the 

 tail of the parasite for its head, and considered the appen- 

 dages of the pi eon to be ramified plumose antennae. 

 Evidently Latreille was puzzled by the description, for in 

 1825, under the genus ' Ichthyophile (Gijrivjthoa, Leach),' 

 he says, ' L'ergina ceruicornis- de M. Risso me parait etre 

 un ichthyophile, ayant accidentellement un corps etranger 

 (algue ?) aux antennes.' In this species it is observed 

 that ' the colour of the ovary and consequently that of the 

 largest part of the body is of a brilliant carmine red.' 



Gigcmtione, Kossmann, 1881. The female has an 

 almost circular outline, all the segments having un- 

 branched prolongations. The three-jointed first antennaB 

 have the basal joint expanded so as to cover the oral 

 region, just leaving space for the protrusion of the points 

 of the mandibles. The tiny feet have a short pointed 

 nail. The marsupial plates are very large. The first 

 pleopods form acuminate sacks with sparingly ramified 

 out-growths on the surface ; the following pairs are small, 

 entirely ramose. The male has the pleon distinctly seg- 

 mented, with six pairs of oval sack-like pleopods. 



Gigcmtione Moebii, Kossmann, 1881 (see Plate XVIIL), 

 in Rilppellia wipressa, de Haan. 



lone, Latreille, 1818. The female has the side-plates 

 well developed '^n the head and perason, those of the first 

 five segments of the pleon arborescent, coralloid, the ap- 

 pendages of the sixth segment simple, cylindrical, recurved 

 at the extremity. The male has the second antenna3 seven- 

 jointed, and the pleon furnished with six pairs of long 

 cylindrical appendages. 



lone thoracicus (Montagu, 1808), in Ccdlianassa sub- 

 terranea (Montagu), was first recorded from Devonshire. 



lone cornutiis, Spence Bate, 18G4, in Ccdlianassa longi- 

 mana, Spence Bate. 



Io7ie vicina, Giard and Bonnier, 1890, in Ccdlianassa 

 truncata, Giard and Bonnier, 



lone gehice, Giard and Bonnier, 1890, in Tlpogehia stellata 

 (Montagu). 



