Rhachotropis 349 



Bäte, Cat. Amphip. Brit. Mus., p. 151 t. 28f. 5 | 18(37 Amphitonotus e., Packard in: Mem. 

 Boston Soc, v.l p. 297 | 1882 Tritropis avirostris, (r. 0. Sarsin: Forh. Selsk. Cliristian., 

 nr. 18 p. 105 t. 5 f. 8 | 1888 Rhachotropis aculeatus (pari.) -f- R. avirostris (part.), 

 T. Stebbing in: Rep. Voy. Challenger, v. 29 p. 49, 954; p. 540. 



Penieon segmentsl — 5. dorsal cariua faintly indicated in large specimeiis, 

 Segment 6 with 3 teeth, segment 7 and pleon segments 1 — 4 triply carinate, 

 carinae produced into sharp teeth except the lateral of segment 4, which, 

 liowever, like the 5*^ and 6*^, has a small lateral tooth. Peraeon segment 7 has 

 lateral corners acute. Central carina forms 2 successive teeth on each 

 of pleon Segments 1 — 4. Head with dorsal hump, rostrum nearly reaching 

 end of 1^* Joint of antenna 1, acute, channelled above, carinate below, lateral 

 corners with a triangulär, somewhat deflexed lobe. Side-plate 1 concave below, 

 front corner acute, 1^* — 3*^ with bind corner acute, 5^^ and 6*^ slightly ridged 

 behind. Pleon segment 3, lateral margin very finely serrate. Eyes large, convex, 

 rounded triangulär, dark brown. Antenna 1, .1^* Joint large, as long as 

 2^ and 3*^ combined, with apical tootli, 3*^ very short, 2*^ and 3^ calceoli- 

 ferous, flagellum longer than peduncle, with about 65 short joints, each with 

 calceolus; accessory flagellum 2-jointed. Antenna 2 rather longer, ultimate 

 and penultimate joints of peduncle subequal, calceoliferous, flagellum longer 

 than peduncle, with about 85 calceoliferous joints. Gnathopods 1 and 2 nearly 

 equal, ü^^ Joint powerful, palm defined by obtuse spiniferous tooth, finger 

 long, evenly curved. Peraeopods 1 — 5 moderately slender. Peraeopods 3 

 and 4, 2^ Joint rather small, bind margin proximally produced to acute 

 triangulär process. Peraeopod 5, 2*^ Joint broad above, bind margin angular 

 above the middle, acutely produced at apex. üropods 1 and 2, outer ramus 

 much the shorter; uropod 3, outer ramus a little the shorter, both narrowly 

 lanceolate; all the rami closely spinulose. Telson very long, tapering, 

 closely margined with spinules, cleft '/s of length, apices approximate, acute. 

 Colour variegated with brown, orange and pure white, gnathopods 1 and 2 

 carmine. L. 30 — 44 mm. 



Arctic Ocean (widely distributed, circumpolar, reaching lat. 82" 27' N.). Depth 

 19—263 m. 



2. K. kergueleni Stebb. 1888 R. k., T. Stebbing in: Rep. Voy. Challenger, 

 t'.29 p.955 t.85 [ 1893 R. k., Gr. 0. Sars, Crust. Xorway, v.l p.424 | 1893 Acanthozone k., 

 A. Della Valle in: F. Fl. Neapel, v. 20 p. 612 t. 59 f. 24. 



Peraeon very short, pieon segments 1 — 4 long, tiicarinate, each produced 

 into a dorsal tooth, largest on segment 2, segments 1 and 2 with smaller 

 tooth on each side. Head, rostrum very long, narrow, subdepressed, lateral 

 corners naiTOw, prominent. Side-plate 1 produced üjiguiform, 4*^^ moderately 

 excavate, 5*^^ and 6*"^ slightly serrate behind. Pleon segment 3, lateral 

 margin firmly serrate. Eyes not perceived. Antenna 1, 1^* and 2^ joints 

 subequal, 3^ not ^^ as long as 2'^, flagellum much longer than peduncle, with 

 34 joints, those of distal half very slender, accessory flagellum not perceived. 

 Antenna 2 longer, penultimate Joint of peduncle long, fringed with plumose cilia, 

 ultimate much longer, flagellum longer than peduncle, abruptly narrower, 

 with 37 slender joints. Mandible, molar rather small, palp very large. 

 Gnathopods 1 and 2 similar, gnathopod 2 the larger; 5*^ Joint with distal lobe 

 well produced, very spinöse, 6*^ large, broadly oval, distally naiTOwed, palm 

 well defined by spinöse tooth, finger long, much curved. Peraeopods 1 — 5 

 veiy slender. Peraeopods 3 and 4, 2^ Joint very small, in peraeopod 5 



