Micruropus 



39!» 



iu leugth, Hccessory fiagellum 1-jointed. Guathopods 

 not greatly diflfering in size. üropod 3 small or very 

 üuter ramus usually 1-jointed. Telsou cleft. 



12 species. 

 Synopsis of species: 



(All Segments dorsally unarmed — 2. 



) Some Segments with dorsal setules or spinules — 3. 



I Eyes rather large; uropod J not reaching beyond 

 2 ' uropod 3 1. 



l Eyes very sm all; uropod 1 reaching beyond uropod 3 2. 



i All Segments anterior to pleon segment i dorsally 

 . ) smooth - 4. 



j Some Segments anterior to pleon segment 4 dorsally 



' armed — 5. 



I Uropod 1 not reaching beyond middle of uropod 3 3. 



I Uropod 1 reaching end of uropod 3 4. 



. j Antenna 1, peduncle shorter than in antenna 2 — 6. 



) Antenna 1, peduncle not shorter than in antenna 2 — 7. 



I Antenna 1 shorter than antenna 2; uropod 3, inner 



) ramus half as long as outer 5. 



I Antenna 1 longer than antenna 2; uropod 3, inner 



' ramus scarcely ^s as long as outer 6. 



) Peraeou dorsally minutely granulär 7. 



1 Peraeon dorsally smooth — 8. 



j Antennael and2, incjand?, flagellum with calceoli 



) Antennae 1 and 2, flagellum without calceoli — 9. 



j Antenna 1 longer than antenna 2 — 10. 



\ Antenna 1 not longer than antenna 2 11. 



j Uropod 3, inner ramus iiearly as long as outer . . 



\ Uropod 3, inner ramus only half as long as outer 



I Gnathopod 2, 6th Joint piriform 



) Gnathopod 2, 6th joint oblong 



1 and 2, 6"' Joint 

 small, rami unequal 



6 



M. pvxella . 

 M. inflatus 



M. vortex . . 

 M. talitroides 



M. littoralis . 



M. glaber . . 

 M. rugosus 



«. M. wahlii . 



p. 399 



p. 400 

 p. 400 



. p. 401 



. p.401 



. p. 402 



. p.402 



9 



10 



11 



1. M. puella (ßyb.) 1874 Gammarusp., B. Dybowsky in: Horae Soc. ent. Koss.. 

 t?.10 suppl. p. 48, 175 I 1893 Atylus? p., A. DellaYalle in: F. Fl. Neapel, v. 20 p. 930 1899 

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



All Segments dorsally completely smooth and level. Side-plates 1 — 4 

 each with 3— 5 setules. Eyes rather large, reniform, ruby-red. Antenna 1 -/s 

 as long as body, more than twice as long as antenna 2, peduncle a little longei* 

 than peduncle of antenna 2, flagellum 1 2 — 14-jointed. Antenna 2, flagellum 

 with 3 or 4 joints. Gnathopod 1, 6*'' Joint piriform, in ö larger than the 

 oblong 6^^ Joint of gnathopod 2. Peraeopods 3 — 5-, 2^^ Joint broad, rather 

 convex iu front, strongly widened behind, the almost semicircular wing 

 ending below in a short rounded lobe, setules on both margins. üropod 1 



reaching end of uropod 3. Uropod 3 '/^j 



or ^/j2 as long as body, outer 



ramus 2-jointed, 2*^ Joint ^^ as long as 1^*, with 2 apical setae, 1^* Joint 

 with 1 marginal spine and 2 apical spines; inner ramus ^2 ^^ long as outer, 

 with 2 apical setae. Telson cleft. Colour white. L. 5 — 6 mm. 



Lake Baikal. Depth 100 m. 



2. M. inflatus (Dyb.) 1874 Gamniarus L, B. Dybowsky in: Horae Soc. ent. 

 Ross., ulO suppl. p. 169 t. 12 f. 4 ! 1893 Atylus? l, A. Della Valle in: F. Fl. Neapel, 

 0.20 p.929 ; 1899 Micruropus i., T. Stebbing in: Tr. Linn. Soc. London, ser.2 v.7 p.424. 



