Pallasea 379 



spinules on bind margin. Head, upper surface a little rough, under margin 

 of lateral lobes produced into an acute tooth. Eyes strongly protuberant, brown. 

 Antenna 1 nearly 72 as long as body, about ^/g longer than antenna 2, peduncle 

 longer tban flagellum, flagellum 26 — 32-jointed, accessory flagellum 4-jointed. 

 Antenna 2, flagellum 8-jointed. Gnathopods 1 and 2, 6*^ Joint piriform. 

 Peraeopod 5, 2*^ Joint twice as long as broad, narrower than usual in the 

 genus. üropod 3, outer ramus about ^/j „ longer than inner, both rami setose. 

 Telson rather long, with many lateral setules and shallowly concave apical 

 margin. Colour brown, with white spots and bands. L. 33 mm. 



Lake Baikal. Depth 10 — 50 m. 



8. P. brandtii (Dyb.) 1874 Gammarus b., B. Dybowsky in: Horae Soc. ent. 

 Küss., V. 10 suppl. p. 186 1. 14 f. 1 I 1893 Ceradocus? b., A. Della Valle in: F. Fl. Neapel, 

 t'.20 p. 927 I 1899 Pallasea b., T. Stebbing in: Tr. Liun. Soc. London, ser. 2 v.l p. 422. 



Peraeon and pleon with 2 parallel median rows of tubercles, peraeon 

 Segments 1 — 7 each with marginal carina formed by a low, flattened, rounded 

 tubercle, above which the lateral humps, successively higher, pass over into 

 Short, backward directed teeth; corresponding with and continuing the marginal 

 and lateral carinae of the peraeon are ridges and teeth on the sides of pleon 

 Segments 1 — 3, but on segment 3 the median tubercles and the lateral tooth 

 are more feebly, while the ridge is more strongly developed than in segments 1 

 and 2. Head uncommonly large and tumid, rostrum very short, margin of 

 lateral lobe thickened and caiinate, a downward directed boss behind the 

 eyes. Side-plates 3 — 4 have little tubercles. Eyes round or oval, strongly 

 protuberant, as if stalked. Antenna 1 nearly half as long as body, and twice as 

 long as antenna 2, 1^* Joint thick, 3*^ variable, never less than half as long as P*, 

 longer or shorter than 2"*, or equal to it, flagellum 30 — 45-jointed, accessory 

 flagellum4— 6-jointed. Antenna 2, flagellum 9 — 12-joiuted. Gnathopod 1,6*^ Joint 

 piriform. Gnathopod 2, 6*^ Joint oblong, widening somewhat to the oblique 

 palm. Peraeopod 5, 2^ Joint oval, rather wider above than below, marginal 

 setae veiy short. Uropods 1 and 2 with setae on the margins and 1 — 3 

 spinules at the apices of the rami. üropod 3, inner ramus scarcely shorter 

 than outer, both carrying many setae. Telson cleft to the middle (beyond 

 it in figure), forming 2 tube-like lobes with the apices beut one to meet the 

 other. Colour: head, peraeon segments 6 and 7, pleon segments 4 — 6 bright 

 green, other segments brownish. L. reaching 35 mm. 



Lake Baikal. Depth 10 — 50 m. 



9. P. grubii (Dyb.) 1874 Gammarus g., B. Dybowsky in: Horae Soc. ent. Boss., 

 f. 10 suppl. p. 132 t. 1 f. 5 I 1893 Crangonyx? g., A. Della Valle in: F. Fl. Xeapel, v. 20 

 p. 928 j 1899 Pallasea g., T. Stebbing in : Tr. Linn. Soc. London, ser. 2 v. 7 p. 422. 



Peraeon segments 1 — 4 or 1 — 5 with 2 parallel nredian rows of tubercles 

 separated by a groove; on the other peraeon segments the tubercles fonn 

 a Single median row, continued by a weak median carina on pleon segments 1 — 3; 

 on peraeon segments 1 — 5 the marginal carina is represented by thick, broad, 

 feebly flattened humps, on segments 6 and 7 by quite feeble, small humps; 

 the lateral carinae begin on peraeon segment 1 with very weak humps, 

 encreasing on the following segments, and on 5 — 7 or 6 and 7 running out 

 into short teeth; pleon segments 1 and 2 have each a pair of long, backward 

 bent teeth, as in P. quadrispinosa (p. 377), and segment 3 has a lateral swelling. 

 Head, upper surface rough, with median groove, bounded behind by 2 little 

 tubercles; the sides below have a boss-like prominence. Eyes roundish oval, 



