67 



hooked, abruptly curved in the middle, and terminating in a very sharp point. 

 The 4 posterior pairs of legs very slender, with the propodal joint elongated, and 

 the dactylus hook-shaped. Uropoda with the basal part but slightly produced 

 inside, terminal plates comparatively narrow, setiferous. 



Remarks. This genus, established by 0. Harger, is nearly allied to Ro- 

 cinela, but differs in the total absence of eyes, and in the abruptly narrowed 

 metasome, as also in the structure of the mandibles. In some other points, for 

 instance, the strongly hooked pereiopoda, it seems to form a transition to the 

 family Cymothoidce (sens, strict.). The genus is as yet only represented by a 

 single species. 



Syscenus infelix, Harger. 



(PI. XXVIII.) 



Sybcenns wfdlx. Haryer, Report on the marine Isopoda of New England. Rep. Un. St. Coin. 



Fish & Fisheries Part VI, p. 387. 



Syn : Harponyx pranizoides, G. 0. Sars. 

 Rocinda Lilljeborgii, Bovallius. 



Specific Characters. Immature form: Body very slender and much de- 

 pressed, with the anterior division oblong oval in form, the posterior one much 

 narrower, and sublinear. Cephalon triangular, gradually narrowed in front to a 

 somewhat projecting point, First segment of mesosome rather large, last segment 

 much narrower than the preceding ones, and without coxal plates. Metasome fully 

 as long as the mesosome, very slightly widening posteriorly, terminal segment 

 about the length of the other 5 combined, and gradually tapering to an obtuse 

 point carrying 2 juxtaposed spines, edges fringed with slender bristles. Superior 

 antennae with the flagellum about the length of the peduncle, and 5-articulate ; in- 

 ferior ones 3 times as long, with the flagellum twice the length of the peduncle, 

 and composed of 11 articulations, clothed posteriorly with long and slender setae. 

 Anterior pairs of legs comparatively short and stout, with the dactylus enormously 

 developed; the 3 posterior pairs very slender, and rapidly increasing in length, 

 6th pair about the length of the whole body, not including the caudal fan, pro- 

 podal joint in all 3 pairs very much elongated, dactylus strong, hook-shaped. Last 

 pair of legs wanting. Pleopoda with the lamella? comparatively narrow, inner one 

 of the posterior pair not ciliated. Uropoda with the basal part somewhat elongated, 

 and produced inside to a rather short setiferous projection, terminal plates narrow 

 oblong, and fringed with slender bristles, the outer one considerably smaller than 

 the inner, and armed outside with a row of small spiuules. Colour whitish, pel- 

 lucid, cephalon tinged with light chestnut. Length 6 mm. 



