498 Parapallasea 



1. P. borowskii (Dyb.) 1874 Gammarus b. -|- G. b. var. dichrons -f- G. b. subvar. 

 abyssalis, B. Dybowsky in: Horae Soc. enl. Ross., u 10 suppl. p. 139 t. 2 f. 3 j 1893 

 Ceradocus? b., A. Della Valle in: F. Fl. Neapel, ».20 p. 927 ] 1899 Farapallasea b., T. 

 Stebbing in: Tr. Liun. Soc. London, ser. 2 v.7 p. 429. 



Peraeon and pleou segments with weak marginal swellings, peraeon 

 Segments 5 — 7 and pleon segments 1 — 6 each with a pair of lateral teeth 

 on bind margin, as a rule pointing backward and outward, not unfrequently' 

 the first 2 pairs bent uncinately outward or forward; tbe teeth short, onlj 

 on pleon segments 1 — 3 somewhat longer, on pleon segments 4 — 6 hump- 

 like, each with 3 spinules, and between these humps is a median flat carina 

 with 1 or 2 spinules on the hinder end. Head smooth, upper profile convex, 

 rostrum short. Ejes slightly protuberant, reniform, black. Antenna 1 

 more than half as long as body, twice as long as antenna 2, 1^* Joint long, 

 but not as long as 2'^ and 3*^ combined, flagellum 52 — 7l-jointed. accessory 

 flagellum 10- or 11-jointed. Antenna 2, flagellum 17 — 20-jointed. Gnatho- 

 pod 1, 6*''^ Joint piriform. Gnathopod 2, 6*'^ Joint oblong, with convex bind 

 margin. Peraeopods 3 — 5, 2^ Joint narrowly heai-t-shaped, in peraeopod 5 

 twice as long as broad. üropod 3, outer ramus about ^/g longer than inner, 

 both with long stout setae on the margins. Telson broader than long, divided 

 to the base, apices of the conical lobes wide apart, tipped with spinules. Colour 

 bright flesh-red or orange-red, differing in the varieties. L. reaching 56 mm. 



Lake Baikal. Depth 50 to below 1000 m. 



2. P. lagowskii (Dyb.) 1874 Gammarus L, B. Dybowsky in: Horae Soc. ent. 

 Ross., V. 10 suppl. p. 140 t. 2 f. 2 j 1893 Ceradocus? L, A. Della Valle in: F. Fl. Neapel, 

 t>.20 p. 929 I 1899 Parapallasea l, T. Stebbing in: Tr. Linn. Soc. London, ser. 2 v.7 p. 429. 



Body laterally compressed, peraeon and pleon segments with marginal 

 swellings, which are much more weakly developed on the pleon, lateral processes 

 thick, on peraeon segments 1 — 5 as outgrowths with their ends directed 

 outward and forward, on peraeon segments 6 and 7 and pleon segments 1 — 3 

 as thick, pointed, backward directed teeth, on pleon segments 4 — 6 as 

 streng humps, each with 4 or 5 spinules. Head feebly convex, rostrum 

 almost flat. Side-plates 1 — 4 rather deep. Eyes extremely small, almost 

 point-like, white. Antenna 1 more than half as long as body, twice as long 

 as antenna 2, 1^* Joint long, flagellum 63-jointed, accessoiy flagellum 10-jointed. 

 Antenna 2, flagellum 22-jointed. Gnathopod 1, 6*^ Joint pirifomi. Gnathopod 2, 

 6*^ Joint oblong, with thickened bind margin. Peraeopods 3 — 5, 2*^ Joint 

 heart-shaped, in peraeopod 5 nearly thrice as long as broad. üropod 3, 

 outer ramus about ^e longer than inner. Telson cleft to the base. Colour 

 white or bright flesh-red, offen with darker spots. L. reaching 64 mm. 



Lake Baikal. Depth 800-1300 m. 



3. P. puzyllii (Dyb.) 1874 Gammarus p., B. Dybowsky in : Horae Soc. ent. 

 Eoss., nlO suppl. p. 141 t. 3 f. 4 I 1893 Ceradocus? p., A. Della Valle in: F. Fl. Neapel, 

 v. 20 p.930 1 1899 Parapallasea p., T. Stebbing in: Tr. Linn. Soc. London, ser. 2 v.l p.429. 



Peraeon segments 1 — 6 and pleon segments 1 — 3 each divided into 

 a dorsal compartment, with concave bind margin, and 2 lateral compartments 

 at right angles to the dorsal, the Separation effected by a pair of low, 

 wing-like, outward directed, lateral carinae; on pleon segments 4 — 6 the 

 lateral carinae are tubercular, surmounted by 4 or 5 spinules. Head with 

 the convex upper surface separated from the sides by obscure lateral carinae, 

 the rostral point small, depressed. Side-plates 1—4 moderately deep. Eyes 



