Micruropus 403 



Eyes moderately large, broadly roniform, not prominent, black. Antenna 1 

 about ^8 ^ long as body, nearly twice as long as antenna 2, but peduncle, 

 though stouter, scarcely longer, flagellum 16-jointed. Antenna 2, flagellum 

 4- or 5-jointed. Gnatbopods 1 and 2, 6*'' Joint sniall, piriform in guathopod 1, 

 oblong in gnathopod 2. Peraeopods 3 and 4. 2*^ Joint narrow, front margin 

 littlo convex, with fascieles of long setae, bind margin setose, wing-like 

 oxpansion very weakly developed. Peraeopod 5, 2^ Joint very broad, in ö 

 only ^7 longor than broad, lower part of front margin almost monstrously 

 l)nlging, Upper surface of the swelling closely set witb long setae. Uropods 1 

 and 2 moderately long, in d botb reaching beyond uropod 3, in Q uropod 2 

 somewbat shorter. Uropod 3, outer ramus as long as peduncle, with 2 or 3 

 apical spines and 4 pairs on outer margin. inner ramus only about ' ^ shorter, 

 with 2 or 3 apical spines. Telson cleft. Colour white, with a lougitudinal dorsal 

 dark stripe. L. about 9 mm. 



Lake Baikal. 



10. M. perla (Dyb.) 1874 Gamniarusp., B. Dybowsky in: Horae Soc. ent. Ross., 

 V. 10 suppl. p. 184 : 1893 Atylus? p., A. Della Valle in: F. Fl. Neapel, u 20 p. 929 ; 1899 

 Micruropus p., T. Stebbing in: Tr. Linn. Soc. London, ser. 2 u 7 p. 424. 



Peraeon segments smooth, pleon segmeuts with scattered dorsal setules. 

 Head, rostral point short, rounded, slightly depressed. Side-plates 1 — 4 

 with few setae. Eyes punetiform or linear, white, becoming invisible in 

 spirit. Antenna 1 about V4 ^^ long as body and ^l^ longer than antenna 2, 

 peduncle rather longer than peduncle of antenna 2, P* Joint broad, flagellum 

 rather shorter than peduncle, 7- or 8-joiuted, accessory flagellum 1-jointed. 

 Antenna 2, flagellum 4- or 5-jointed. Gnathopod 1, 6**^ Joint oval, rather 

 larger than the oblong 6*^^ Joint of gnathopod 2. Peraeopods 3 — 5, lower front 

 corner with fascieles of stift" setae: tliis Joint in peraeopods 3 and 4 very 

 narrow, above broader than below, bind margin sinuous, in peraeopod 5 very 

 broad, wider below than above. Uropod 1 reaching rather beyond uropod 2, 

 both beyond uropod 3. Uropod 3 about ^j^^ as long as body, outer ramus 

 shorter than peduncle or equal to it, with 2 or 3 apical spines, inner ramus 

 half as long, sometimes with an apical seta. Telson cleft. Colour white. 

 L. d 9, 9 7 mm. 



Lake Baikal. Depth 10 m. 



11. M. klukii (Dyb.) 1874 Gammarus k., B. Dybowsky in: Horae Soc. ent. 

 Ross.. r. 10 suppl. p.l81 | 1893 Atylus? k., A. Della Valle in: F. Fl. Neapel, r. 20 p.929! 

 1899 Micruropus k., T. Stebbing in: Tr. Linn. Soc. London, ser. 2 v.l p. 424. 



Pleon Segments 4 — 6 with 2 or 3 groups oi- delicate spinules, back 

 otherwise quite smooth. Side-plates 1^ — -4 setiferous. Eyes narrowly reniform, 

 black. Antenna 1 .only ^j^ as long as body, rather shorter than antenna 2. 

 1^* Joint broad, flat. 2*^ and 3"^ thin. flagellum with 10 joints, 1^* rather 

 long, and as long as 1-jointed accessory flagellum. Antenna 2. flagellum 

 4- or ö-jointed. Gnatbopods 1 and 2 equal, 5**^ Joint piriform. Peraeopod 3, 

 2* Joint broader below than above, bind margin with upper and lower corners 

 rounded. Peraeopod 4, 2'^ Joint wider above than below. Peraeopod 5, 

 2** Joint wider below, bind margin evenly rounded, and as in peraeopods 3 

 and 4 setose. Uropod 3 7, ^ as long as body, but reaching beyond uropods 1 

 and 2, outer ramus 1-jointed, 4 or 5 times as long as inner, with 5 spines 

 and 3 setae on the apex, a spine and a .seta on outer margin, inner ramus 



26* 



