502 Oarinogammarus 



Synopsis of accepted species: 



f Uropod 3, inner ramus not short — 2. 

 \ Uropod 3, inner ramus short — 6. 



f Body carinate throughout — 3. 

 \ Body only partially carinate — 4. 



IAntenna 1, accessory flagellum 3-jointed; gnatho- 

 pod 2, 6th Joint oblong 1. C. cinnamomeus . p. 502 

 Antenua 1, accessory flagellum 12-jointed: gnatlio- 

 pod 2, ßtli Joint piriform 2. C. wagii p. 502 



j Eyes halfmoon-shaped 3. C. pulehellus . . p. 503 



] Eyes oval — 5. 



f Peraeopod 5, 2<i Joint widened distally 4. C. seidlitzii . . . p. 503 



\ Peraeopod 5, 2d Joint naiTOwed distally .... 5. C. rhodophthalmus p. 504 



Pleon Segments 4 and 5 with erect spinöse dorsal 



tubercle 6. C. caspius . . . . p. 504 



^ Pleon Segments 4 and 5 without erect dorsal 

 tubercle — 7. 



J At least 2 of tlie peraeon segments carinate . . 7. C. atehensis . . . p. 505 

 ) At most 1 of the peraeon segments carinate — 8. 



Q J Pleon segments 1 — 3, carina tipped with spines . 8. C. subcarinatus . p. 505 

 \ Pleon segments 1 — 3, carina acute, without spines 9. C. roeselii . . . . p. 506 



1. C. cinnamoineus (Dyb.) 1874 Gammarus c, B. Dybowsky in: Horae Soc. 

 ent. Ross., u 10 suppl. p. 114 t. 7 f. 3 | 1899 Carinognmmarus c, T. Stebbing in: Tr. 

 Linn. Soc. London, ser. 2 v.7 p. 429 | 1893 Gammarus fluviatilis (part.)?, A. DellaValle 

 in: F. Fl. Neapel, u 20 p. 928. 



Body laterally compressed, its upper surface rough, with delicate hairs in 

 various parts; all segments dorsally provided with a distinct though weak 

 median carina, occupying the whole length of the segments in peraeon 

 segments 4 — 7 and pleon segments 1 — 3; hind margin of pleon segments 

 4 — 6 provided with 8 groups of tolerably strong spines, set on hump-like 

 elevations. Head, front rounded, little prominent. Side-plates without setae 

 on lower margin. Eyes rather large, prominent, reniform, black. Antenna 1, 

 peduncle thicker and somewhat loiiger than that of antenna 2, or rarely 

 shorter; with flagellum nearly ^2 ^^ long as body, and almost twice as 

 long as antenna 2; flagellum 21 — 28-jointed, accessory flagellum 3-jointed. 

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

 Gnathopod 2, 6*'' Joint oblong. Peraeopods 3^5, 2^ Joint heart-shaped, 

 with very short setae wide apart on hind margin. uropod 3 rather long, 

 the outer 2-jointed ramus V8~~V2 longer than the inner, 2^ Joint more than 

 ^4 as long as 1®*, inner ramus longer than peduncle, both rami with plumose 

 setae on inner and simple on outer margin. Colour cinnamou-brown. L. 18 mm. 



Lake Baikal. Depth 50—100 m. 



2. C. wagii (l)yb.) 1874 Gammarus la., B. Dybowsky in: Horae Soc. ent. Ross., 

 ulO suppl. p. 121 t. 1 f. 4 I 1893 Ceradoctis? w., A. Della Valle in: F. Fl. Neapel, v. 20 

 p. 931 I 1899 Carinogammarus to., T. Stebbing in: Tr. Linn. Soc. London, ser. 2 v.7 p.429. 



Median carina developed over the whole body, on the head appearing 

 as an obscure rounded ridge-line, and gradually encreasing in height to 

 pleon Segment 3, from peraeon segment 5 ruuning out into an acute, back- 

 ward and upward directed angle; this carina occupies the whole dorsal length 

 of each segment, is tolerably high, strongiy compressed laterally, with convex 



