241 ■ Üediceros 



Back of peraeou broad. Rostrum deflexed, acute. Eyes distinct, contiguous. 

 at base of rostrum. Antenna 1 shorter than autenna 2, peduncle of each 

 elongate. Upper lip rounded. Mandible, molar without triturating surface. 

 palp robust. Maxilla 1, inner plate witli a few setae, outer plate narrow. 

 Maxilla 2, plates oval, subequal. Maxillipeds, outer plates sti'ongly friuged 

 with spines. Gnatliopods 1 and 2 similar and nearly equal, 5*^ Joint produced 

 to a setose lobe, 6*^ oval, palm very oblique. Peraeopods 1 — 4 short, stout. 

 setose, finger lanceolate. Telson rounded quadrangular. 



2 species accepted, 1 doubtful. 



Synopsis of accepted species: 



Kostrum geniculate 1. O. saginatus . p. 244 



Rostrum gently curved 2. O. borealis . . p. 244 



1. O. saginatus Kroyer 1842 0. s., Kreyer in: Naturh. Tidsskr., i'. 4 p. 156 [ 

 1883 O.S., J.S.Schneider in: Trorase Mus. Aarsh.. v. 6 p. 11 t. 2 f. 10 | 1892 0. s., 

 G. ü. Sars, Crust. Xorway, v.l p.288 t. 102 | 1893 0. s. (part.), A. Della Valle in: F.Fl. 

 Neapel, i/.20 p. 551 t. 58 f. 71, 72. 



Head, rostrum abruptly deflexed, acute, nearly reaching apex of P* Joint 

 of antenna 1; lateral corners quadrate. Side-plates not deep, 4*^^ scarcely 

 emarginate behiud, 5*^ broader and nearly as deep. Eyes within a rounded 

 prominence, dark red. Antenna 1, 1***^ and 2*^ joints equal in length, 

 flagellum scarcely as long as peduncle, 13-jointed. Antenna 2, ulti- 

 mate Joint of peduncle as long as penultimate and antepenultimate com- 

 bined, flagellum rather shorter than peduncle. Gnathopods 1 and 2. 

 process of 5*^ Joint slightly curved and a little dilated in the middle, densely 

 tufted, 6*^1 Joint oblong oval, more than twice as long as broad, palm 

 denticulate, long, gently curved, defined by a little tooth, finger long and 

 curved. Peraeopods 1 — 4, finger rather short. Peraeopod 5 more than half 

 length of body, 2^ Joint with sinuous bind margin. üropod 3, inner ramus 

 rather the longer, with 4 spinules. Telson little longer than broad, ' apex 

 transversely truncate. Colour whitish, tinged with orange, head reticula,te 

 and back banded with brown violet. L. 20 — 30 mm. 



Arctic Ocean and North-Atlantic (Greenland, Iceland, Spitzbergen, Murman 

 coast, Siberian Polar Sea, Norwaj). 



2. O. borealis Boeck 1871 0. h., A. Boeck in: Forh. Selsk. Christian., 1870 

 p. 162 I 1876 0. h., A. Boeck, Skand. Arkt. Amphip., x: 2 p. 261 t. 14 f. 1 | 1892 0. b., 

 G. 0. Sars, Crust. Norway, ».1 p. 290 t. 103 f . 1 11893 0. saginatus (part.), A. Della 

 Valle in: F. Fl. Neapel, v. 20 p. 551. 



Head, rostrum evenly curved downward, reaching little beyond middle 

 of 1^* Joint of antenna 1 ; lateral corners rounded, Side-plates rather large, 

 l''* somewhat pentagonal, 4*^ distinctly emarginate, deeper than 5^'^ Eyes 

 rather small, contiguous. Antenna 1, flagellum 10-jointed. Antenna 2, 

 ultimute Joint of peduncle scarcely longer than penultimate, flagellum subequal to 

 peduncle. Gnathopods 1 and 2 very streng, process of 5*^ Joint narrow, spariugly 

 setose, 0*^ tumid, oval, palm not veiy long, defined by a little tooth, finger 

 to match the palm. Peraeopods 1—4 less stout than in 0. saginatus, finger 

 in peraeopods 3 and 4 rather long. Peraeopod 5, 2*^ Joint rounded oval, bind 

 margin scarcely sinuous. üropod 3 rather small, rami very narrow, inner 

 with 1 spinule. Telson much longer than broad, apex broadly rounded. 

 L. 9 9 mm. 



Arctic Ocean (Greenland, Finmark). 



