416 



edge armed with a single rather strong spine, outer with a much smaller spine 

 in addition to the marginal bristles. 



Colour not "yet ascertained. 



Length of adult female 0.84 mm. 



Remarks. This form was also at first described by Th. Scott as a species 

 of the genus Tetragoniceps, though the specific name proposed would seem to 

 indicate the doubt he had felt in referring it to that genus. In its external 

 appearance the present form more resembles the type species of Tetragoniceps 

 than do the other 2 forms treated of in the preceding pages. 



Occurrence. Only very few specimens of this form have as yet come 

 under my notice. One of these, a fully developed male, was found in a sample 

 kindly sent to me by Mr. Nordgaard, who procured it from the Trold Fjord, 

 inside the Lofoten islands. The other specimens were derived from samples taken 

 last summer at Korshavn from depths of from 30 to 50 fathoms. 



Distribution. Scottish coast (Scott). 



Gen. LeptaStaCUS, Scott, 1906. 



Generic Characters. Body very narrow, but with rather hard integu- 

 ments. Rostrum small, but well defined. Caudal rarni more or less produced. 

 Anterior antennae slender, unarmed. Posterior antennae with the proximal 

 joint not subdivided, outer ramus very small, uniarticulate. Anterior lip very 

 prominent. Mandibles with the masticatory part securiformly dilated and coarsely 

 dentate, palp small, simple. Maxillae with the palp unusually prolonged and 

 without any traces of exopodal and epipodal lobes. Anterior maxillipeds more 

 slender than usual, and having the apical part well defined. Posterior maxillipeds 

 powerfully developed, with the basal joint short and unarmed, propodos exceed- 

 ingly large and tumid, dactylus thin and accompanied at the base outside by a 

 slender bristle. 1st pair of legs very small and imperfectly prehensile, inner 

 ramus shorter than usual, and biarticulate. The 3 succeeding pairs of legs very 

 slender, with_the inner ramus of moderate size and biarticulate; outer ramus of 

 4th pair much more elongated than in the other pairs. Natatory setae in all 

 pairs much reduced in number. Last pair of legs comparatively small and 

 acutely produced inside, distal joint very small or quite wanting. 



Remarks. This genus established by Th- Scott is especially distinguished 

 by the powerful and peculiar development of the posterior maxillipeds. It also 

 differs conspicuously in the structure of the other oral parts and in that of the 



