282 



Gen. LeuCOthoe, Leach, 1813. 



Syn. Lycesta, Savigiiy. 



Body glabrous and not veiy compressed. Cephalon witli a very small 

 and obtuse rostral projection, from wbich a thin vertical lamella descends 

 between the bases of the superior antennae. The 4 anterior pairs of coxal 

 plates but little different in size, and rather broad in proportion to their 

 depth; the 3 posterior pairs much smaller. Antennae rather slender, with 

 elongated peduncles and short flagella. Epistome forming in front a coni- 

 cally pointed projection. Anterior lip with the right lobe much larger than 

 the left; posterior lip with the lateral corners narrowly rounded. Mandibles 

 very strong, cutting edge of the left one provided with a distinct secondar}' 

 lamella dentated on the edge, that of tbe right with no such lamella, palp 

 scarcely longer than the mandible and rather narrow, its terminal joint com- 

 paratively small and simple. First pair of maxillae with the palp distinctly 

 biarticulate, last joint not expanded di.stall3^ basal lobe very small, with 

 only a single bristle; 2nd pair with the inner lobe much broader than the 

 outer. Maxillipeds with the basal lobes short and broad, partly coalesced; 

 1st joint of the palp large and laminar, inner edge sharpened and forming 

 at the end a slight lamellar expansion as a rudiment of a masticatory lobe, 

 terminal joint long and claw-like. Anterior guathopoda rather slendc-r, carpus 

 greatly swollen in its proximal part to receive the powerful muscles moving 

 the propodo.-*, and produced at the end inferiorly to a claw-like process, 

 which forms the thirmb of the chela, propodos narrow and very movably 

 articulated to the carpus, dactylus small and curved. Posterior guathopoda 

 very powerful, especially in the male, cai'pns short, but produced at the end 

 inferiorly to a setous lobe, stretching along the hind margin of the propodos, 

 the latter very large and dilated in the middle, palm oblique, dactylus strong 

 and curved. The 3 posterior pairs of pereiopoda subequal both as to size 

 and structure. Second pair of uropoda much shorter than the other 2; last 

 pair with the basal part elongated, rami lanceolate and minutely spinulose. 

 Telson triangular, imarmed. 



Memarls. — This genus was etablished as early as 1813 by Leach 

 to include the rather divergent form first described and delineated by 

 Abildgaard as Gammarus sxnnicarpus. Besides this form, M. Edwards estab- 

 lished another species undoubtedly belonging to this genus, viz., L. fiiriim, 

 and recently the Rev. Mr. Stebbing has described 3 new species from 

 the Challenger Expedition. A 6th species was moreover established 



