810 Pleustes 



Synopsis of accepted species: 



Peraeon tricarinate, carinae medio-dorsal and latero- 



marginal 1. P. panoplus . . . p. 310 



Peraeon quinquecarinate, with 5 longitudinal rows of 



teeth or tubercles 2. P. eataphractus . p. BIO 



1. F. panoplus (Kröyer) 1838 Amphithoe panopla, Kröyer in : Danske Selsk. Afh., 

 V. 7 p. 270 t. 2 f. 9a— i | 1846 Amphitoe p., Ereyer in: Voy. Nord, Crust. t. 11 f. 2a— x j 

 1859 Paramphithoe p., R. M. Bruzelius in: Svenska Ak. Handl., n. ser. v.3 nr. 1 p. 69 ! 

 1862 Pleustes panoplus, Bäte, Cat. Amphip. Brit. Mus., p. 63 t. 9 f. 9 | 1874 P. p., 

 ßuchholz in: Zweite D. Nordpolarf., v.2 p.334 Crust. t. 6 j 1893 P.p., G. 0. Sars, Crust. 

 Norway, v.\ p. 344 t. 121 ] 1894 P. panopla, T. Stebbing in: Bijdr. Dierk., u 17 p. 28 

 (synonymy) j 1893 Acanthozone p. (part.), A. DellaValle in: F. Fl. Neapel, v. 20 p. 607 

 t. 59 f. 19 I 1867 Amphithonotus eataphractus (err., non Stinipson 1853!), Packard in: 

 Mem. Boston Soc, v. 1 p. 298. 



Back dorsally carinate, strongly on peraeon, which also has lateral 

 margius carinate; pleon segments 1 — 4 and 6 with a pair of dorsal projections, 

 lst__3d ^j|;]j .^ tubercle on each side below these. Rostrum large, obtuse or 

 subacute, sligbtly hollowed dorsally, carinate below; lateral corners of head 

 subquadrate. Side-plate 4 acute angled below emargination, 5*^ and 6*^ 

 with quadrate bind lobe. Pleon segmeut 3 with postero-lateral angles acute, 

 sligbtly produced. F^yes rather sraall, rounded oval, prominent, dark red. 

 Antenna 1 short, 1^* Joint about as long as 2^ and 3*^ combined, flagellum 

 scarcely thrice as long as peduncle, with 26 — 45 joints. Antenna 2 still 

 shorter, ultimate and penultimate joints of peduncle subequal, ttagellum 

 subequal to peduncle, with 20 — 2G joints. Gnathopod 1, palm much longer 

 tban bind margin of 6*^ Joint, tinger only reaching P* of 3 trausverse rows 

 of palmar spines. Gnathopod 2 more powerful, narrow lobe of 5**^ Joint 

 more projecting, G*^ much more dilated at junctiou of palm with bind 

 margin (Sars appears to reckon the palms not from this angle, but from the 

 point reached by the finger). Peraeopods 3 — 5, 2*^ Joint oblong quadrangular. 

 üropod 3 not very long, inner ramus not twice leugth of outer. Telson 

 at base constricted and having on the upper face a triangulär prominence, 

 apical margin broadly rounded. Colour dark brown, or whitish, or variegated 

 with shades of brown. L. 9 reaching 18—27 mm. 



Arctic Ocean (widely distributed, depth 5 — 113 m); Nortli-Atlantic (West-Norway 

 from Bergen northwards, depth 19^56 m; South of Halifax [Nova Scotia], depth 155 m). 



2. P. eataphractus (Stimps.) 1853 Amphithonotus c., Stimpson in: Smithson. 

 Contr., w. 6 nr. 5 p. 52 | 1876 Paramphithoe cataphracta, S. I. Smith & Harger in: Tr. 

 Connect. Ac, » 3 p. 31 | 1876 Tritropis eataphractus, A. Boeck in: Skand. Arkt. Amphip., 

 i?.2 p.510 I 1888 Rhachotropis c. T. Stebbing in: Rep.Voy. Challenger, u29 p.278, 1720. 



Body robust. Kostrum very large, elongate triangulär, pointed, 

 curving downwards, concave above and with a sharp median ridge below. 

 One strong median dorsal carina coramencing on peraeon segment 1, 

 becoming strongly dentate on -the last peraeon segment, and ceasing on 

 pleon segment 2; the next 2 carinae (proceeding outwards) are developed 

 in the form of strong teeth on peraeon segments 6 and 7 and all pleon 

 Segments, being spine-like on pleon segment 2, and almost lamelliform on 

 the last 4; the next carinae are sharp ridges, extending along the bases 

 of the side-plates, and sligbtly contiuued on pleon segments 1 and 2; and* 

 the last or outer carinae are very short, extending only along the bases of 



