348 Rhachotropis 



More or less of the body dorsally and subdorsally carinate. Head 

 rosti-ate. Side-plates rather small, 1^* narrowly produced forward, 4*'' veiy 

 slightly emarginate. Pleon segment 3, postero-lateral corners rounded, 

 seiTate above. Antenna 1 geuerally shorter tban aiiteniia 2, and sometimes 

 with small 2-joiuted accessoiy flagellum. Antenuae 1 and 2 larger in ö 

 than in Q . Mouth-parts nearly as in f^usirus (p. 338). JVIaxilla 1, outer 

 plate witb 9 spines (sometimes 8?). Gnathopods 1 and 2 strong, subequal, 

 5*^ Joint Short, cup-shaped, 6*^ large, oblong oval, palm very oblique. 

 Peraeopods 1 — 5 slender, long, 5*^^ very long, its 2*^ Joint larger tban that 

 in 3^ and 4*^ pairs. Uropod 3, rami foliaceous. Telson long, more or 

 less cleft. 



11 species. 



Synopsis of species: 



fPeraeopod 5, 2d Joint acute at lower bind 

 angle — 2. 

 Peraeopod 5, 2<i Joint not acute at lower hind 

 angle — 3. 



I Telson cleft for more than a quarter of its 

 length 1. R. aeuleata . . . . p. 348 

 Telson cleft for less than a quarter of its length 2. R. kergueleni . . . p. 349 



{Pleon Segments 1—3 having some of the dorsal 

 teeth upturned — 4. 

 Pleon Segments 1 — 3 not having some of the 

 dorsal teeth upturned — 5. 



f Antenna 1 without accessory flagellum ... 3. R. griraaldii . . . . p. 350 

 \ Antenna 1 with 1-jointed accessory flagellum 4. R. elegans p. 350 



f Eyes well developed — 6. 



) Eyes not well developed — 9. 



I Antenna 1, 3d Joint very short 5. R. oculata p. 350 



\ Antenna 1, 3d Joint not very short — 7. 



Peraeon segment 7 and pleon segment 3 without 



medio-dorsal tooth 6. R. inflata p. 351 



Peraeon segment 7 and pleon segment 3 with 



medio-dorsal tooth — 8. 



Peraeopod 5 not so long as the body ... 7. R. heller! p. 351 



Peraeopod 5 longer than the body 8. R maeropus . . . . p. 352 



Eyes rudimentary 9. R. leueophthalma . p. 353 



Eyes wanting — 10. 



f Pleon tricarinate on segments 2—4 10. R. rostrata .... p. 353 



\ Pleon not tricarinate 11. R. gracilis p. 353 



10 



1. ß. aeuleata (Lepech.) 1780 Oniscus aculeatus, Lepechin in: Acta Ac. 

 Petrop., 17781 p. 247 t. 8 f . 1 | 1866 Amphithonotus a., Goes in: Üfv. Ak. Förh., i\22 

 p.526 I 1874 A. a. (part.), Buchholz in: Zweite D. Xordpolarf., v.2 p.3l6 Crust. t.4 | 1871 

 Tritropis aeuleata, A. Boeckin : Forh. Selsk. Christian., 1870 p. 158 1 1872&76 Aeanthonotus 

 aculeatus -\- T. aeuleata. A. Boeck, Skand. Arkt. Amphip., ».1 p. 37; v.2 p. 511 j 1883 

 Rhachotropis aeuleata, B. aeiilata, S. I. Smith in : P. U. S. Mus., v. 6 p. 229, 222 | 1893 

 R. aeuleata, G. 0. Sars, Crust. Norway, v. 1 p. 424 t. 149 | 1894 R. aculeatus, T. Stebbing 

 in: ßijdr. Dierk., u. 17 p. 37 | 1893 Pontogeneia aeuleata {part.). A. Della Valle in: F. FL 

 Neapel, t).20 p.616 t. 59 f. 28 ! 1821 Talitrus edvardsii, E.Sabine, An. north. Exp., p. 55 t.2 

 f. 1 — 4 I 1835 Amphithoe edvardsi, J. C. ßoss in: John Ross. App. sec. Voy., nat. Hist. 

 p. 90 1 1846 A. edicardsii, Kreyer in : Naturh. Tidsskr., ser. 2 v. 2 p. 76 | 1862 Amphithonotus e.. 



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