tJristes, Centromedon 65 



quadrate, 4*^ without any dorsal projectiou. Eyes narrow, sigmoid, light red, 

 evanescent in spirit, Antenna 1, 1^* Joint rather elongate, flagellum stout, of 

 25 joints, 1*** largest, not very large, accessory flagellum almost filiform, of 

 6 small joints. Antenna 2 rather longer than antenna 1, ultimate Joint of 

 peduncle longer than penultimate, flagellum not very stout, 23-joiuted. Epistome 

 not projecting. Gnathopod 1, 6*^ Joint much longer than 5^^, oblong, palm very 

 oblique, ill-defined, 7^ii Joint about half as long as 6*^ Gnathopod 2, 6*^^ Joint 

 rather broader than 5*^, and more than half as long. Telson tapering rauch, 

 carrying 2 pairs of dorsal spinules. Colour whitish. L. 11 mm. 



Arctic ücean, North-Atlantic and North-Sea (West-Norway), Skagerrak. Depth 

 55—790 m. 



39. Gen. Centromedon 0. Sars 



1891 Centromedon (Sp. typ.: C. pumilus), G. O. Sars, Crust. Xorv\ ay, v.l p. 99 | 

 1893 C, J. Bonnier iu: Bull. sei. France Belgique, V.2A p. 173. 



Head, lateral angles acutely produced. Side-plates deep. Pleon segment 3, 

 postero-lateral angles acutely upturned. Eyes imperfect or wanting. Antenna 1 

 and 2 in 9 stout, subequal. Epistome not projecting. Mandible, molar 

 conical, palp rather large, affixed over molar. Maxiila 1, inner plate with 

 2 setae, outer with usual^ spines, apex oblique, palp with few spines on apex. 

 Maxiila 2, inner plate a little shorter than outer. Maxillipeds, outer plates 

 not reaching end of 2'^' Joint of palp, which has the 4*^ Joint small. Gnatho- 

 pod 1 stout, imperfectly subchelate. Gnathopod 2 subchelate. Peraeopods 3 — 5, 

 2*^ Joint large; 5*^^ peraeopod much shorter than 4*^, üropod 3 rather small, 

 rami without marginal setae. Telson oblong, deeply cleffc, with 2 pairs of 

 apical spinules. 



4 species. 



Synopsis of species: 



[ Peraeopod 5, 2d Joint with lower hind corner acute 1. C. calcaratus . p. 65 

 1 l Peraeopod 5, 2d Joint with lower hind corner 

 l rounded — 2. 



j Head, lateral angles slightly upturned 2. C. productus . . p. 66 



) Head, lateral angles straight pointed — 3. 



J Pleon segment 4 with rounded carina ....... 3. C. pumilus. . . p. 66 



\ Pleon segment 4 with pointed carina 4. C. typhlops . . p. 66 



1. C. calcaratus (0. Sars) 1879 Anonyx c, Hippomedon?, G. 0. Sars in: 

 Arch. Xaturv. Kristian., v.A p. 440 | 1885 A. c, Gr. O. Sars in: Norske Nordhavs-Exp., 

 V. 6 Crust. I p. 142 t. 12 f. 3 | 1893 A. c, A. Della Valle in: F. Fl. Neapel, v. 20 p. 829 j 

 1891 A. c, Centromedon?, G. 0. Sars, Crust. Norway, v.l p. 100. 



Head, lateral angles produced to a straight spine-like point. Side- 

 plate 1 not narrowed below. Pleon segment 3, postero-lateral angles acutely 

 upturned to a greater extent than in any other species of the genus, 4*'^ without 

 carina. Eyes wanting, unless represented by a diffuse whitish-yellow pigment. 

 Antenna 1, peduncle rather stout, flagellum with 9 joints, 1^* not very long, 

 accessory flagellum 3-jointed. Antenna 2 about as long as antenna 1, ultimate 

 Joint of peduncle much shorter than penultimate, flagellum 9-jointed, Gnatho- 

 pod 1, 6**^ Joint longer than 5*^, rather nan*ow, tapering, palm undefined. Gnatho- 

 pod 2, 6*11 JQJjj^ comparatively broad, palm not produced. Peraeopods 1 and 2, 

 7*^ Joint almost straight. Peraeopods 3 and 4, 2"^ joint oval. Peraeopod 5, 2^^ Joint 

 rather quadrate, the lower hind corner outdrawn to a spine-like point. üropod 3 



Das Tierreich. 21. Lief.: T. R. R. Stebbiug, Amphipoda I. 6 



