242 



apparatus present, Male (or last larval stage) resembling in outward appea- 

 rance that of other Cryptoniscidse, though distinguished by the presence of well- 

 developed eyes, the want of teeth on the basal expansion of the antennulse, and 

 by the poor development of the last 2 pairs of legs. Parasitic on rizocephalic 

 Cirripedia. 



Remarks. This genus was established as early as in the year 1843 by 

 H. Rathke, to include a small Crustacean, which he erroneously referred to the 

 Amphipoda, but which has turned out to be the male (or last larval stage) of a 

 parasitic Isopod. The female was only detected many years afterwards (1858) 

 by Prof. Lilljeborg, who at first made out the life-history of this peculiar Cru- 

 stacean. As the generic name Liriope proposed by H. Rathke has been appro- 

 priated by Lesson to designate a genus of Medusae, Dr. Mac Schultze has changed 

 it to Liriopsis. Though evidently belonging to the family Cryptonistidce, this 

 genus differs in several points rather markedly from the other forms, both as 

 regards the structure of the female and that of the male. Besides the northern 

 species described below, a 2nd nearly-allied form has been recorded by Dr. Fraisse 

 from the gulf of Naples under the name of L. monophthalma. 



Liriopsis pygmasa (Rathke). 



(PL XCIX, fig. 3, PI. C., fig. 1). 



Liriope pygmcea, H. Rathke Beitr. z. Fauna Norwegens, p. 60, PI. 1, flgs. 8 12 (male). 



Liriope pygmosa, Lilljeborg, Les genres Liriope et Peltogaster, p. 6, PI. 1 (female). 



Syn: Cryptothiria pygmsea, Sp. Bate Westwood. 



Specific Characters. - Anterior immerged section of the body securiformly 

 expanded, or almost seinilunar in form, convex above and plane below, consist- 

 ing of 4 segments, the defining lines being well distinguishable on the dorsal side; 

 posterior exposed section globular in form, with a groove along the middle of 

 the ventral face. Male (or last larval stage) moderately slender, gradually 

 narrowed behind, dorsal face smooth and shining. Cephalic segment evenly ar- 

 cuate in front; anal segment rounded behind. Eyes very distinct, each consisting 

 of a dark pigment within which is imbedded a single rather large, refractive 

 lenticular body. Antennulse comparatively robust, 1st joint of the peduncle pro- 

 jecting in front to a strong denticle, and forming behind a very large linguiform 

 expansion without any traces of teeth or setse, 2nd joint with the front edge 

 divided into 2 small denticles. Antennas well developed, extending to the end of 

 the 4th pedigerous segment. Coxal plates not pectinate. The 5 anterior pairs 

 of legs of the usual structure; the last 2 pairs, on the other hand, very small, 



