Parapallasea, Amathillina 499 



small, roundish, veiy prominent, advauced in front of rostrum between 

 antennae 1 and 2, black. Antenna 1 neaiiy half as long as body, almost 

 twice as long as antenna 2, 1^* Joint elougate, subequal to 2^ and 3*^ combined, 

 flagellum 40 — 47-jointed, accessory flagellum 5 — 7-jointed. Antenna 2, 

 flagelium 14 — 16-jointed. Gnathopod 1, 6*^ Joint piriform. Gnathopod 2, 

 6^^ Joint oblong. Peraeopods 3 — 5, 2^ Joint elongate, heart-shaped, with rather 

 long remote setae on bind margin. üropod 3, outer ramus about \ longer 

 than inner. Telson cleft to the base. Colour red. L. reaching 53 mm. 



Lake Baikal. Depth 50—500 m. 



49. Gen. Amathillina 0. Sars 



1894 Amathillina (Sp. typ.: A. cristata) (AmathilUnella O. Grimm in MS.), G. 0. 

 Sars in: Bull. Ac. St.-Petersb., ser. 5 u 1 p. 201. 



Body more or less carinate, pleon segments 5 and 6 witb subdorsal 

 spinules. Head, rostrum short, lateral lobes short, obtuse, post-antennal 

 Corners acute or rectangular. Side-plates 1 — 4 of moderate size, 4**^ much 

 the largest, distinctly emarginate. Pleon segments 2 and 3, postero-lateral 

 Corners quadrate. Antenna 1 the longer, 3*^ Joint not very short, accessory 

 flagellum 2 — 6-jointed. Mouth-parts normal. Gnathopods 1 and 2 subequal. 

 Peraeopod 4 the longest, its 2*^ Joint moderately expanded, but much less; 

 than that of peraeopod 5. üropod 3 rather short, outer ramus with small 

 narrow 2'^ Joint, inner ramus small, scale-like. Telson short, broad, cleft to 

 the base. 



5 species. 



Synopsis of species: 



J Pleon segments, median dorsal carina rounded — 2. 

 I Pleon Segment 3, median dorsal carina triangulär — 3. 



/ Median dorsal carina beginning on peraeon seg- 



) ment 1 1. A. cristata .... p. 499 



j Median dorsal carina beginning on peraeon seg- 



' ment 6 2. A. pusilla . . . . p. 500 



f Pleon segment 3, carina low . 3. A. maximoviczi . p. 500 



\ Pleon segment 3, carina elevated — 4. 



Pleon segment 4 with small rounded dorsal ex- 



pansion 4. A. spinosa . . . . p. 501 



Pleon segment 4 with no dorsal expansion ... 5. A. affluis . . . . p. 501 



4i 



1. A. cristata 0. Sars 1894 A. c. (AmathilUnella c. O. Grimm in MS.). G. 0. 

 Sars in: Bull. Ac. St.-Petersb., ser. 5 ». 1 p. 202 t. 5; t. 6 f. 1—8. 



Body stout, little compressed, carina low -on peraeon segment 1, 

 gradually encreasing to broad triangulär projections, important in size on 

 peraeon segments 6 and 7 and pleon segments 1 and 2 ; the carina of pleon 

 segment 3 evenly rounded. Pleon segments 4 — 6 each dorsally carrying a 

 few simple hairs, segments 5 and 6 each with subdorsal spinules, 2 on each 

 side. Head, rosti-um blunt, lateral lobes broadly truncate, post-antennal 

 Corners acutely projecting. Eyes rather small, narrowly reniform, dark. 

 Antenna 1, peduncle long, 1^* Joint not greatly longer than 2^, nor 2^ than 

 3*i, flagellum longer than peduncle, 20 — 25-jointed, accessory flagellum about 

 5-jointed. Antenna 2 much shorter, flagellum more than half as long as 

 peduncle, 12-jointed. Gnathopods 1 and 2 in 9 small, subequal, setose; 



32* 



