322 



Coxal plates of moderate size, and successively increasing to the 4th pair. 

 Eyes distinct, and of an appearance similar to those in the genus Monoculodes. 

 Superior antennae very unlike in the two sexes, in female rather slender, though 

 somewhat shorter than the inferior ones, in male very robust, the peduncle 

 being greatly tumefied, and the 1st joint of the flagellum of enormous size. 

 Inferior antennae in both sexes of the very same structure. Oral parts 

 resembling those in the genus Monoculodes, except that the masticatory lobes 

 of the maxillipeds are comparatively shorter and broader. Gnathopoda rather 

 strong, and not very unequal in structure, propodos in both pairs subcheli- 

 forrn and oval in shape, carpal lobe in the posterior ones somewhat narrower 

 than in the anterior. Pereiopoda of the usual structure. Last pair of uropoda 

 greatly elongated, and projecting far beyond the other 2 pairs. Telson 

 very small. 



Eemarks. This genus, established by Boeck, is nearly related to the 

 genus Monoculodes, differing however, in a few points, very markedly, thus in 

 the much smaller size of the masticatory lobes of the maxillipeds, the nearly 

 equal structure of the gnathopoda, and the extremely elongated last pair of 

 uropoda; finally the male is highly characterised by the peculiar modification 

 of the superior antennae, whereas the inferior ones are not at all different from 

 those in the female. The genus comprises as yet but a single species, to be 

 described in the sequel. 



23. Halicreion longicaudatus, Boeck. 



(PI. 113, fig. 2). 

 Helicreion longicaudatus, Boeck, Crust, amph. bor. & arct. p. 93. 



Body moderately slender and somewhat compressed. Cephalon nearly 

 as long as the first 3 segments of mesosome combined, its upper contour 

 forming a perfectly even curve until the tip of the rostrum, the latter some- 

 what compressed, and extending a little beyond the basal joint of the superior 

 antennas, lateral corners of cephalon somewhat produced, but obtusely rounded 

 off at the tip. First pair of coxal plates scarcely expanded distally and, like 

 the 3 succeeding ones, oblong quadrangular in form; 4th pair somewhat 

 deeper than the corresponding segment and not very broad, infero-posteal 

 corners not at all produced; 5th pair somewhat broader but much less deep. 

 Eyes oval in form, placed just above the base of the superior antennae, 

 visual elements imperfectly developed, pigment light red. Superior antennae 

 in female attaining the length of the cephalon and the first 3 segments of 

 mesosome combined, and reaching about to the end of the peduncle of the 



