5021 



tlie sea. Subsequently I have also met with it in the Christianiafjord, at 

 Moss, where it occurred in quite shallow water among algae. 



Distrihufion. — British Isles (Leach), Kattegat (Copenhagen Museum). 



11. Gammarus Duebeni, Lilljeborg. 



(PI. 177, fig. 1). 



Gam>narus Dueheni, Lilljeborg, 0fvera. af Kgl. Svenska Vet. Acad. Forhandl. 1851, p. 22. 



Syn. : Gammarus campylops, NoriBan (not Leach). 

 » — locusta, var. C, Hoek. 



Form of body about as in G. locusta. Cephalon having the lateral 

 corners, as in G marittus, transversely truncated, and defined below by a rather 

 deep sinus. Coxal plates smaller than in G. locusta, and more nearly similar 

 to those in G. marinus. Last pair of epimeral plates of metasome but 

 slightly produced at the lateral corners. Segments of urosome scarcely 

 produced dorsally, and each provided with 2 dorsal spines, and on either side, 

 with a group of 3 spines, being moreover clothed with numerous rather long 

 hairs. Eyes not very large, and distinctly reniform, as in G- locusta. Superior 

 antennae not quite half as long as the body, 1st joint of the peduncle scarcely 

 attaining the length of the other 2 combined, flagellum about twice the length 

 of the peduncle, accessory appendage not nearly half as long as the latter, 

 and composed of about 6 articulations. Inferior antennae considerably shorter 

 than the superior, flagellum about the length of the last 2 joints of the 

 peduncle, and in male provided with distinct oalceolae. Gnathopoda in female 

 somewhat resembling those in G. locusta, though the propodos of the posterior 

 ones appears less narrow; those in male not nearly so strongly developed 

 as in that species, and also less unequal in size. The 3 posterior pairs of 

 pereiopoda comparatively less -slender tlian in the 2 preceding species, and 

 having their outer part clothed with fascicles of rather long bristles; basal 

 joint of antepenultimate pair rounded at the infero-posteal corner. Last pair 

 of uropoda with the inner ramus but little exceeding half the length of the 

 outer, both rami densely setiferoua. Telson rather broad, each half with 4 

 apical spines, 1 subapical (sometimes wanting on one of the sides), and from 2 to 4 

 lateral spines near the base, and being besides clothed with long diverging 

 hairs. Body generally of a very dark colour, with 3 pink patches on each 

 side of the metasome, as in G. locusta. Length of adult male 15 mm., that 

 of female considerably less. 



