10 



Gen. 3. ParathemistO, Boeck, 1870. 



Body somewhat compressed, but with the back scarcely carinated. 

 Cephalon irregularly rounded; mesosome moderately vaulted; metasome well 

 developed, with large epimeral plates. Antennae in female subequal, more 

 elongated than in the preceding genera; in male about as in Hyperia. 

 Anterior lip with a large unequally bilobed buccal plate ; posterior lip with the 

 lobes densely ciliated, lateral corners produced. Mandibles rather strong, 

 cutting edge very broad and minutely denticulated, molar expansion rather 

 large, regularly serrate on the edge, palp with the middle joint very elongated. 

 First pair of maxillae with the palp rather expanded, inner edge denticulated 

 and terminating with a small tooth-like projection. Terminal lobes of the 

 maxillipeds acuminated and beset with scattered long setse. Grnathopoda 

 densely hirsute and rather dissimilar; 1st pair simple, with the carpal joint 

 rather broad and not produced inferiorly; 2nd pair subchelate, the carpal 

 joint being produced to a narrow process, which does not, however, reach the 

 end of the propodal joint; dactylus of both pairs rather elongated. The 2 

 anterior pairs of pereiopoda having the carpal joint only slightly dilated; the 

 3 posterior pairs very slender, subequal, with the carpal and propodal joints, 

 especially the latter, greatly elongated and almost naked. Ilropoda more 

 slender than in the preceding genera. Telson comparatively small. 



Remarks. - - This genus, established by Boeck, is very nearly related 

 to the succeeding one, Eutliemisto, and ought perhaps to be combined with it. 

 The distinctive characters are chiefly the equal-sized antennae of the female, the 

 less powerful structure of the 2 anterior pairs of pereiopoda and the uniform 

 development of the 3 posterior ones. Besides the northern species described 

 below, the HIHHTUI- frir/ona of Dana would seem to belong to this genus, as also 2 

 new species described, the one by Bovallius, the other by the Rev. Stebbing. 



4. Parathemisto oblivia, (Kroyer). 



(PI 5, fig 1). 



Hypcria oblivia, Kroyer, Gr0nlands Amphipoder, 1 c. p. 70, pi. 4, tig. 19. 

 Syn : Parathemisto abyssorum, Boeck. 



Body moderately slender, with the 1st segment of the mesosome 

 much longer than the 2nd. Cephalon rather large, only slightly more deep than 

 long; eye-pigment oval, very dark. Superior antennae in female about as long 

 as the cephalon and the 1st segment of the mesosome combined, flagellum only 

 very slightly curved, about three times the length of the peduncle. Grnatho- 

 poda with the propodal joint about as long as the carpal one; carpal process 

 of 2nd pair very narrow, reaching beyond the middle of the propodal joint; 



