171 

 5. Ampelisca gibba, G. 0. Sars. 



(PI, 69, tig. 2). 

 Ampelisca gibba, G. O. Sars, Oversigt af Norges Crustaceer, I. p. 107, PI. 6, fig, 1. 



Ceplialon about the length of the 3 anterior segment.? of mesosome 

 comliineil, evenly tapering distally, and narrowly truncated at the tip, lower 

 corner but little projecting. First pair (jf coxal plates gradually widening 

 lielow, terminal edge nearly transversely truncated; 4th pair somewhat 

 narrower than in A. laviyata. Last pair of epimeral plates of metasome 

 ])roduced at the lateral corners to an acute projection, posterior edge slightly 

 arcuate in the middle. First segment of urosome exhibiting, at the end dorsally, 

 a very conspicirous hump-like comjjressed projection, which in the male is 

 still nrore prominent, and nearly erect. Corneal lenses distinct, the lower 

 pair ])laced a little behind the inferior corners of the front; underlying pig- 

 ment well-defined, and bright red. Superior antennge in female rather small, 

 scarcely reaching beyond the penultimate peduncular joint of the inferior ones, 

 2nd joint of the peduncle much more elongateil and slender than in A. Iwvic/ata, 

 flagellum about the length of the peduncle, and composed of only 6 articula- 

 tions; those in male somewhat longer, though scarcely reaching beyond the 

 middle of the last peduncular joint of the inferior ones. The latter in female 

 not quite as long as the body, and extremely slender, the 2 outer joints of 

 the peduncle narrow and elongated, the last one a little shorter than the 

 penultimate. Both pairs of gnathopoda slender and feeble, especially the 

 l)osterior ones. Anterior pairs of pereiopoda with the meral joint far less 

 expanded than in ^1. Icevir/ata, dactylus long and narrow. Last pair of j)ereio- 

 poda witli the basal joint about eijualling in length the remaining part of 

 the leg, posterior expansion obtusely truncated at the ti]), outer part of the 

 leg somewhat resembling that of A. Icevigata, but with the deflexed lobe of 

 the meral joint considerably smaller, and bearing only 3 setse at the tip. 

 Last pair of uropoda with the rami much narrower, and nearly naked. Telson 

 in female rather short and broad, nearly obcordate in form, and somewhat 

 dilated in the middle, outer part triangularly tapering, with a double series 

 of about 5 bristles somewhat within the edges dorsally; that in male con- 

 siderably narrower. Body highly pellucid, and nearly colourless, except 

 for a few small yellowish speckles in the anterior jiart; ova in the 

 marsupial pouch of a beautiful orange-coloiir. Length of adult female 8 mm, 

 of male 7 mm. 



BeinarJct:. — This species is nearl>- allied to A. Iceiiijata, though easily 

 tlistinguishable, not only by its much smaller size, but also hy the rather 

 diiferent form of the cephalon, and liv the very conspicuous hump-like dorsal 

 projection of the 1st segment nf urosome. 



