Neopleustes, Mesopleustes 315 



•middle of palp's 2^ Joint, palp's 3*^ Joint tapering distally, finger spine-like. 

 'Gnathopods 1 and 2, 5*^ Joint short, triangulär, lobe rounded, 6*** Joint very large, 

 oval, widest at junction of subequal palm and bind margin, larger in 

 gnathopod 2 tban in guatbopod 1. Peraeopods 3 — 5. 2^ Joint large, feebly 

 serrate, 4*^ Joint produced downward. Uropod 3, peduncle very short, rami 

 spinöse, outer about ^/^ as long as inner. Telson oval. L. ?. 



North-Pacific (California). 



3. Gen. Mesopleustes Stebb. 



1899 Mesopleustes (Sip. typ.: Fleustes abyssorum), T. Stebbing in: Ann. nat. Hist., 

 ser. 7 u 4 p. 209. 



Coating indurated, carinate. ßostrum large. Side-plates 1 — 4 distally 

 narrowed, 5*^ and 6*^ with bind lobe deeper tban front. Upper lip with small 

 oblique incision. Mandible, accessory plate on both left and right, molar 

 prominent, strong, oval, 3"^ Joint of palp longer tban 2^. Maxilla 1, inner 

 plate with 2 short and 2 long phimose setae, outer plate with 10 spines. 

 Maxillipeds, inner plates with 3 spine-teeth in a group at apical angle, outer 

 plates scarcely reaching beyond 1*** Joint of palp, inner raargin unarmed, 

 apical with G close-set spines, 1^* and 2^^ joints of palp equal, 3"^ rather 

 shorter, as long as strong finger. Gnathopods 1 and 2 sti'ong, 5**^ Joint 

 cup-like, G*^ broad oblong oval, palm well defined. Gnathopod 2 larger 

 than gnathopod 1. Peraeopods 1 — 5 robust, subequal. Telson subrotund. 



1 species. 



1. M. abyssorum (Stebb.) 1888 Bleustes a., T. Stebbing in : Rep. Voy. Challenger, 

 i;.29 p. 872 t. 67 | 1893 Acanthozone a., A. Della Valle in: F. Fl. Neapel," ».20 p. 609 

 t. 59 f. 21 I 1899 Pleustes a., Mesopleustes sp. typ., T. Stebbing in: Ann. nat. Hist., 

 ser. 1 v.-i p. 209. 



In general appearence resembling Pleustes panoplus (p. 310). Peraeon 

 and pleon segments all carinate except 4**» of pleon; segments irabricate, 

 pleon Segment 3 with ereet dorsal tooth. Rostrum long, narrow, carinate 

 below, lateral and post-antennal corners little projectiug. Side-plate 1 

 narrowly produced forward, 2 denticles on bind margin, 2^ — 4*** successively 

 encreasing in depth, vertically ridged, 4*** with very oblique bind margin 

 below emargination, 5*^ with distally narrowed bind lobe. Pleon segment 3, 

 postero-lateral corners produced into a small tooth. Eyes small, oval. Antenna 1, 

 P* Joint a little longer than 2*^, 3^ more than ^/.^ as long as 2*^. flagellum with 

 44 joints, 1^^ longest. Antenna 2 much shorter, ultimate Joint of peduncle 

 rather longer than penultimate, flagellum with 24 joints, 1^* longest. Gnatho- 

 pods 1 and 2 spinöse, 5*^^ Joint as broad as long; gnathopod 1, %^^ Joint 

 with palm divided between 2 broad shallow emarginations, finger reaching 

 beyond them. Gnathopod 2 much larger, palm with deep cavity between 

 its blunt end and a large tooth or process near the finger hinge. Peraeo- 

 pods 1 — 5 nearly as in Sympleustes latipes (p. 317), but 2*^ Joint oblong, bind 

 margin sinuous, with much produced lobe. Uropod 3, outer ramus little 

 longer than peduncle, only half length of inner. Telson short, as broad as 

 long. L. about 17 mm (if fully extended). 



Southern Indian ücean (near Marion Island). Depth 3013 m. 



