378 Pallasea 



apart, segments 4 — 6 without fascicles of spinules. Head, rosti'um minute, 

 lateral lobes smoothly rounded, a boss-like projection overhanging post- 

 antennal coruers. Side-plates 1 — 4 rather narrow, not contiguous below, 

 4*^ "rather less deep than 3*^. Pleon segments 1 — 3, postero-lateral comers 

 rounded (as perhaps throughout the genus). Eyes rounded oval, very dark. 

 Antenna 1 about Vs as long as body, 1®* Joint nearly as long as 2* and 

 3^ combined, flagellum shorter than peduncle, with about 16 (Sars), with 

 24—15 (Dybowsky) joints, accessory flagellum with 2 joints, 2*^ the longer. 

 Antenna 2 rather shorter, ultimate and penultimate joints of peduncle nearly 

 equal, flagellum 6- or 7-jointed. Gnathopod 1, 6*^ Joint piriform. Gnatho- 

 pod 2 rather raore slender, 6*^ Joint oblong oval, palm nearly transverse; 

 both pairs of gnathopods in d stronger than in Q . Peraeopods 3 and 4, 2*^ Joint 

 little expanded, slightly narrowed below. Peraeopod 5, 2"^ Joint larger than 

 in preeeding peraeopods, oval, fringed behind with setae. üropod 1, rami 

 much shorter than peduncle, smooth. üropod 2 much shorter than uropod 1, 

 rami with smooth sides. Uropod 3, outer ramus fringed with fascicles of 

 slender setae, 2^ Joint minute, inner ramus scarcely more than 7s aslong 

 as outer, setiferous on inner margin. Telson a little broadei- than long, 

 3 spinules on each side, emargination ^4 of the length, apices rounded, tipped 

 with a spinule. Colour yellowish grey, each segment banded transversely 

 with. brownish green. L. d 15 — 19 mm. 



Lakes of Norway (Mjös-Sjö, depth 6 — 94 in, and others, also River Vorm), 

 Sweden, and Russia (Finland, Onega). 



6. P. kesslerii (Dyb.) 1874 Gammarus k., B. Dybowsky in: Horae Soc. ent. 

 Ross., nlO suppl. p. ia3 t. 1 f. 7 | 1893 Amathilla? k., A. DellaValle in: F. Fl. Neapel, 

 V.20 p.929 i 1899 Pallasea k, T. Stebbing in: Tr. Linn. Soc. London, ser. 2 v.l p. 422. 



Near to P. quadrispinosa (p. 377). Median carina represented by small 

 tubercles on peraeon segments, peraeon segments 1 — 5 each with supramarginal 

 streng acute tooth, segments 6 and 7 each with only a weak hump over the 

 margin; pleon with additionof a little median tubercle on each of segments 1 — 3, 

 and a flat lateral swelling on segment 3. Head, upper surface rough, 

 with a median groove, narrowing forward; a streng outward and somewhat 

 downward projecting tooth overhanging post-antennal corners. Side-plates 

 carinate. Eyes oval, very prominent, dark brown or black. Antenna 1 half 

 as long as body, nearly twice as long as antenna 2, flagellum 20 — 28-jointed, 

 accessory flagellum 2 — 4-jointed. Antenna 2, 7 — 9-jointed. Peraeopod 3, 

 2"^ Joint sometimes widened below. Uropod 3, inner ramus in adults only 

 about V, shorter than outer, both carry ing on their margins numerous setae, 

 the majority plumose. Telson very feebly emarginate, and very feebly grooved 

 above distally. Colour bright greenish, with black or brownish spots, the 

 appendages banded. L. reaching over 37 mm. 



Lake Baikal. Depth 10—20 m. 



7. P. baikali Stebb. 1874 Gammarus lovenii (non G. loveni R. M. Bruzelius 

 1859!), B. Dybowsky in: Horae Soc. ent. Ross., ».10 suppl. p. 137 t. 13 f. 7 j 1893 

 Pallasea cancellus (part.)?, A. DellaValle in: F. Fl. Neapel, u20 p.929 | 1899 P. baikali, 

 T. Stebbing in: Tr. Linn. Soc. London, ser. 2 v.7 p. 422. 



Median carina wanting, peraeon segments 1 — 5 with marginal teeth, 

 thinner, somewhat longer and more backward curved than in P. cancelloides 

 (p. 380); weak lateral swellings probably represent the lateral carinae;' pleon 

 segments without teeth or humps, segments 4 — 6 each with a couple of small 



