402 Micruropus 



7. M. rugosus (Dyb.) 1874 Gatmnanis r., B. IJybovvsky in: Horae Soc. eiit. 

 Ross., ulO suppl. p. 48, 174 1. 14 f. 8 | 1893 Atylus? r., A. Della-Valle in: F. Fl. Neapel, 

 V.20 p.930 1899 Micruropus r.. T. Stebbing in: Tr. Linii. Soc. London, ser.2 c.7 p.424. 



All peraeon segmeuts and a narrow gii-dle on head dorsally minutely 

 granulär and here and thero beset with short setules. Head with shoii. 

 rounded, rostral point. Side-plates 1 — 4 setose on lower margin. Eyes small, 

 Wide apart, rounded renifonn, black. Antenna 1 scarcely ^/^ as long as body, 

 about ^6 longer than antenna 2, peduncle stouter and a little longer than 

 that of antenna 2. 1''* Joint exceedingly stout, longer than 2*^ and 3*1 combined. 

 flagellum rather shorter than peduncle, 10-jointed; accessoi^ flagellum 

 1-jointed. Antenna 2, ultimate Joint of peduncle shorter than penultimate, 

 flagellum 8-jointed. Gnathopod 1, 6*^' Joint rather longer aud broader than 

 that of gnathopod 2 (oval in gnathopod 1, oblong in gnathopod 2, but in 

 figure very similar), the palm little oblique, well defined, much shorter than bind 

 margin. Peraeopods 3 — 5. 2"^ Joint at lower front corner fringed with fascides 

 of stiff setae ; in peraeopods 3 aud 4 the wing-like widening behind chiefly 

 on the Upper half, in peraeopod 5 the greatest breadth at the lowest quarter. 

 Uropods 1 and 2 reaching beyond uropod 3. Uropod 3 ^i^^ as long as body, 

 outer ramus 1-jointed, as long as peduncle, with 3 apical spines and 2 in 

 middle of outer margin, inner ramus about half as long, with 1 long apical 

 seta. Telson (in figure) nearly twice as broad as long, cleft not nearly to 

 the base, a seta on each divergent apex. Colour brownish white. L. 9 mm. 



Lake Baikal. 



8. M. wahlii (Dyb.) 1874 Gammarus iv. -f- G. ii\ var. lilatycercns, B. Dybowsky 

 in: Horae Soc. ent. Hoss., v. 10 suppl. p. 179; p. 180 | 1893 Atylus? w., A. Della Valle 

 in: F. Fl. Neapel, v.20 p. 931 | 1899 Micruropus u:, T. Stebbing in: Tr. Linn. Soc. 

 London, ser. 2 ij. 7 p. 424. 



Pleon Segments 4 — 6 each with 3 groups of spinules, 2 or 3 in each 

 group on Segments 4 and 5, only 1 or 2 in each on segment 6. Side-plates 1 — 4 

 with setae. Eyes moderately large, reniform, black. Antenna 1 less than ^/g as 

 long as body, usually rather shorter than antenna 2, in var. plaiycercus rather 

 longer, peduncle stouter but shorter, P* Joint stout, flagellum with 21 — 27 joints 

 (in var. with 43). Antenna 2, flagellum with 21 — 27 joints (in var. with 

 31 — 43), as in antenna 1 furnished with calceoli (in antenna 2 smaller in 

 9 than in d). Gnathopods 1 aud 2 witli i\^^ Joint of same size, piriform 

 in gnathopod 1, oblong in gnathopod 2. Peraeopods 3 and 4, 2* Joint little 

 inflated at the setose lower front corner, bind margin closely set with long 

 setae. Peraeopod 5, 2<^ Joint broad. broadest in tlie upper half, with long setae 

 on the bind margin. uropod 3 '/,, as long as body, reaching beyond the 

 others, outer ramus 4 times as long as the inner, with plumose setae on 

 inner margin, 2 pairs of spines and simple setae on the outer, 2*^ Joint 

 Short (not found in var.) ; inner ramus with 2 plumose setae on inner margin 

 and a long apical seta. Telson divided. Colour greenish white. L. 11 mm. 



Lake Baikal (mouth of the river Sljudianka). 



9. M. fixsenii (Dyb.) 1874 Gammarus f., B. Dybowsky in: Horae Soc. ent. 

 Koss., V. 10 suppl. p. 172 I 1893 Atylus? f., A. Della Valle in: F. Fl. Neapel, -c. 20 p.928 | 

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



Pleon Segments 1—6 each with 2 delicate setae on bind margin, 

 otherwise upper surface of body quite smooth and even. Head, upper profile 

 strongly convex, rostrum depressed, beak-like. Side-plates 1-4 with setae. 



