171 

 5. Ampelisca gibba, G. 0. Sars. 



(PI. 59, fig. 2). 

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



Cephalon about the length of the 3 anterior segments of mesosomc 

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

 corner but little projecting. First pair of coxal plates gradually widening 

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

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

 produced 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 conspicuous hump-like compressed projection, which in the male is 

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

 pair placed a little behind the inferior corners of the front; underlying pig- 

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

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

 2nd joint of the peduncle much more elongated and slender than in A. loevigata, 

 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 

 posterior ones. Anterior pairs of pereiopoda with the meral joint far less 

 expanded than in A. leev-igata, dactylus long and narrow. Last pair of pereio- 

 poda with the basal joint about equalling in length the remaining part of 

 the leg, posterior expansion obtusely truncated at the tip, 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 part; ova in the 

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

 of male 7 mm. 



Remarks. - This species is nearly allied to A. hcvigata. though easily 

 distinguishable, not only by its much smaller si/e, but also by the rather 

 different form of the cephalon, and by the very conspicuous hump-like dorsal 

 projection of the 1st segment of urosome. 



