34 Pseudalibrotus, Nannonyx 



2. P. caspius ü. Sars 1896 P. c. (Onesimus c. -\- O. pomposus, 0. Grimm in 

 MS.), O O. Sars in: Bull. Ac. St.-Petersb., ser. b vA p. 422 t. 1 f. 1-20. 



Body rather stout, back strongly curved. Head, lateral lobes naiTowly 

 rounded, Side-plate 1 distally expanded, mucli broader than 2*^ or 3"^. Pleou 

 Segment 3, postero-lateral angles acute, considerably produced. Eyes rather small, 

 rounded oval, probably bright red. Antenna 1, 1®* Joint large. flattened, twice 

 as long as 2^ and 3*^ combined, flagellum about twice as long as peduncle, with 

 löjoints, l^^muchthe largest, with 5 fascicles of filaments, accessory flagellum 

 with 4 joints, 1^* much the longest. Antenna 2 rather longer, ultimate Joint of 

 peduncle not very long, narrower and shorter than penultiraate, flagellum longer 

 than in antenna 1, about 20-jointed. Mouth-parts nearly as in P, litoralis, but 

 palp of mandible attached ' over molar, not in advance of it, palp of maxilliped 

 less robust. Gnathopod 1 not robust, 6*** Joint scarcely as broad as 5*^ soraewhat 

 narrowing distally, palm rather short, with singie spine at the angle, finger small. 

 Gnathopod 2 very slender, 6*^ Joint produced so as to form alittle definite chela. 

 Peraeopods 1 — 5 shorter and less slender than in P. litoralis. Peraeopods 3 — 5, 

 2^ Joint with few serrations on the bind margin. Uropods 1 and 2. rami simple, 

 with scattered spines. üropod 3, peduncle rather short, rami simple, with 

 no 2^ Joint to outer ramus. Telson about as long as broad, apex slightly 

 produced between a pair of notches, each of which carries a setule. L. 9 mm. 



Caspian Sea, middle part. Depth 150 — 470 m. 



3. P. platyceras 0. Sars 1896 P. p. {Onesimus p. O. Grimm in MS.), G. 0. Sars 

 in: Bull. Ac. St.-Petersb., ser. 5 r. 4 p. 426 t. 1 f. 21— 23. 



Very like P. caspius, but twice as long and more tumid, back broadly 

 rounded, pleon segment 4 with marked dorsal depression. Head, lateral 

 lobes subangular. Side-plate 1 comparatively broader than in P. caspius. 

 Pleon segment 3, postero-lateral corners acute, but very little produced. 

 Eyes narrowed above to an obtuse point. Antenna 1, 1^* Joint exceedingly 

 large, conspicuously flattened, flagellum rather slender, with 30 — 40 joints, 

 accessory flagellum with 6 joints. Antenna 2 scarcely longer, flagellum 

 34-jointed. Gnathopod 1, 6*'^ Joint rather shorter in proportion to its breadth, 

 palra less oblique. L. Q 20 mm. 



Caspian Sea, middle part. Depth 75 m. 



20. Gen. Nannonyx 0. Sars 



1871 Orchomene (part.), A. Boeck in: Forh. Selsk. Christian., 1870 p. 114 i 

 1890 & 91 Nannonyx (Sp. un.: N. goesii), G. 0. Sars, Crust. Norway, v. 1 t. 24; p. 71 | 

 1893 N., J. Bonnier in: Bull. sei. France Belgique, ».24 p. 173 i 1893 N., A. Della 

 Valle in : F. Fl. Neapel, v. 20 p. 794. 



Body compact, side-plates large. Mandible elongate, molar obsolete, 

 palp affixed far back. Maxilla 1, inner plate with 1 or 2 small setae, 

 plumose or simple. Maxilla 2, both plates long, narrow. Maxillipeds, inner 

 plates generally elongate, naiTow, outer plates long and broad, slightly crenulate, 

 reaching beyond the 2*^ Joint of palp, 4**^ Joint of palp distinct but rudimentary 

 in size. Gnathopod 1 simple. Gnathopod 2 minutely chelate. Uropod 3 V 

 very small, the outer ramus the longer, 2-jointed. Telson entire. 



5 species. 

 Synopsis of species: 



^ i Maxillipeds, inner plates not elongate or narrow 1. N. spinimanus . . p. 35 

 \ Maxillipeds, inner plates elongate, narrow — 2. 



