380 Pallasea, Weyprechtia 



verv protuberant, dark brown. Antenna 1 less than ^2 ^^ long as body, 

 nearly twice as long as antenna 2, 1^* Joint elongate, flagellum shorter than 

 peduncle, 25 — 29-jointed, accessory flagellum 2- or 3-jointed. Antenna 2, 

 flagellum 8-jointed. Gnathopod 1, 6^^ Joint piriform. Gnathopod 2, 6^*^ Joint 

 oblong. Peraeopods 3 and 4, 2*^ Joint narrow, heart-shaped ; peraeopod 5, 

 2*^ Joint oval ; long and tliick setae on the margin in peraeopods 3 — 5. 

 üropod 3, outer ramus 4^2 times as long as the short, rudimentary inner 

 ramus. Telson with a curved emargination, the upper surface depressed. 

 Colour bright brownish gi-een, with a whitish band over the middle of the 

 back, often segments 2 — 4 darker than others; brownish spots occur; appendages 

 banded. L. reaching 37 mm. 



Lake Baikal. 



10. P. eancelloides (Gerstf.) 1858 Gammarus c, Gerstfeldt in: Mem. pres. Ac. 

 St.-Petersb., v. 8 p. 287 t. 9 f . 8 | 1874 G. c, B. Dybowsky in: Horae Soc. ent. Äoss., v. 10 

 suppl. p. 130 t. 13 f. 6 I 1862 Pallasea c, Bäte, Cat. Auiphip. Brit. Mus., p. 380 | 1893 

 P. cancellus (part.), A. Della Valle in: F. Fl. Neapel, v. 20 p. 755. 



Peraeon segments 1 — 7, median carina weak, tubercular, and ou 

 Segments 1 — 3 inconspicuous, marginal carina niore strongly developed than 

 the lateral, the teeth directed outward and backward, acute, subequal, about 

 twice as long as those of the lateral carina, which are directed backward, 

 those of the 6*** segment longer than the preceding, those of segment 7 

 nearly as long as the marginal teeth; pleon segments 1 and 2 with rather 

 weak median caiina, and on each side a strong, backward and outward 

 bent tooth, longer than the lateral teeth on peraeon, pleon segment 3 with 

 median carina flanked by weak humps, segments 4 — 6 almost smooth. Head 

 tumid, with a prominence at the back, and a strong acute tooth projecting 

 laterally from each cheek. Side-plate 4 with a weak tubercular projection. 

 Eyes very protuberant, oval or broadly reniform, brownish black. Antenna 1 

 about 7* as long as body, about Vg longer than antenna 2, 1^* Joint twice 

 aslongas2'^, 2'^twiceaslongas3*^, flagellum 22 — 26-jointed, accessory flagellum 

 3-jointed. Antenna 2, flagellum 8- or 9-jointed. Gnathopods 1 and 2, 6**^ Joint 

 piriform, narrower and smaller in Q than in d. Peraeopods 3 and 4, 

 2^ Joint elongate quadrangular, rather broader above than below, hind margin 

 somewhat sinuous. Peraeopod 5, 2*^ Joint oval, hind margin as in peraeo- 

 pods 3 and 4 carrying long setae. üropod 3, inner ramus only about ^/g 

 shorter than outer, both with numerous setae, the majority plumose. Telson 

 shallowly emarginate. Colour green or whitish green, with brownish black 

 or brown spots. L. reaching 28 mm. 



Lake Baikal, under stones close to the shore; River Angara at Irkutsk. 



8. Gen. Weyprechtia Stuxb. 



1880 Weyprechtia (Sp. un.: W. mirabüis), Stuxberg in: Bih. Svenska Ak., r. 5 

 nr.22 p. 27 | 1888 W., T. Stebbing in: Rep. Voy. Challenger, r.29 p. 523 i 1894 W., 

 T. Stebbing in: Bijdr. Dierk., f. 17 p.41. 



Body dorsally smooth. Pleon segment 3, postero-lateral margins biden- 

 tate. Antenna 1 the shorter, accessory flagellum 4 — 7-jointed. Upper lip not 

 emarginate. Lower lip, inner lobes not distinct. Mandible, cutting edge 

 little or not dentate, accessory plates dentate, spines of spine-row numerous, 

 molar powerful, 3^ Joint of palp not curved, fuUy as long as 2^ and 3* 

 combined. Maxiila 1, inner plate with setae very numerous, outer with 



