Dikerogammarus 469 



oaspius O. Grimm in MS.), G. 0. Sars in: Bull. Ac. St.-Petersb., ser. 5 v.l p. 215 t. 8; 

 p. 358 1. 12 I 1862 G. caspius (non Oniscus c. Pallas 1771!), Bäte, Cat. Amphip. Brit. 

 Mus., p. 214 t. 38 f. 3 I 1875 G. aralensis, Uljanin in: Fedtschenko, Turkestan, Crust. 

 p. 1 t. 5 f. 15. 



Veiy like D. macrocephalus, differing in the following points. Pleon 

 Segments 4 and 5, dorsal conical tubercle ratber smaller, each with 2 apical 

 spines, segment 4 with a spinule also on each side. Head normal. Pleon 

 Segment 3, postero-lateral corners rather quadrate than acutely produced. 

 Eyes well developed. Antenna 1, accessory flagellum 7 — 9-jointed. Antenna 2, 

 flagellum about 8-jointed. Peraeopods 3 — 5 rather stout. Peraeopod 3, 

 2"^ Joint broader above than below, but nearly quadrangular, lower bind angle 

 slightly produced. Peraeopod 4, 2^ Joint much more expanded above than 

 below. üropod 3, outer ramus with 1 group of spines on inner margin, the 

 small inner ramus more than half as long as the short peduncle. Telson 

 with only 1 or 2 apical spines on the very narrow apex of each lobe. Colour 

 brownish green, bind margins of Segments laterally tinged with pink; eyes 

 dark. L. 9 — 16 mm. 



Black Sea; Caspian Sea (shore to 75 m). 



3. D. grimmi (0. Sars) 1896 Gammariis g., G. 0. Sars in: Bull. Ac. St.-Petersb., 

 ser. 5 V.4: p. 448 t. 6 f. 1 — 10 | 1899 Dikerogammarus g., T. Stebbing in: Tr. Linn. Soc. 

 London, ser. 2 v. 7 p. 428. 



Very like D. haemobaphes. Body rather slender. Pleon segments 

 4 and 5, tubercle veiy prominent, narrow. on segment 4 tipped with 4 spines 

 and flanked by 2 unequal spines on each side, on segment 5 tipped with 

 only 2 spines, segment 6 carrying 3 spines on each side. Pleon segment 3, 

 postero-lateral corners acutely produced. P]yes oblong oval, scarcely reniforra, 

 usually dark, but variable. Antenna 1, accessory flagellum 7-jointed. Gnathopods 

 1 and 2 still more unequal in d than in 9 , gnathopod 2 in €5" very large, 

 6*^ Joint very tumid at the base. Peraeopods 1 — 5 rather slender, 2^ Joint 

 in peraeopods 3 — 5 conspicuously narrower than in D. haemobaphes, in 

 peraeopod 5 this Joint becoming oblong quadrangular, with nearly sti-aight, 

 much serrate bind margin, produced to a narrowly rounded lobe, üropod 3, 

 outer ramus very long and narrow, fringed with setae, but without conspicuous 

 spines; inner ramus about half as long as peduncle, almost spine-like in 

 narrowness. Telson with 2 spinules on each obtusely pointed apex. L. d 27 mm. 



Caspian Sea. Depth 66 — 203 m. 



4. D. verreauxii (Bäte) 1862 Gammarus v., G. verrauxii, {iL. Milne Edwards 

 in MS.?3 Bäte, Cat. Araphip. Brit. Mus., p. 210 t. 37 f. 6 | 1899 Dikerogammarus verreauxii, 

 T. Stebbing in: Tr. Linn. Soc. London, ser. 2 v.l p. 428 | 1893 Gammarus locusta 

 (part.)?, A. Della Valle in: F. Fl. Neapel, r. 20 p. 768. 



Pleon Segments 4 and 5 with dorsal tubercles (without spines in figure). 

 Eyes ovate. Antenna 1 about 7* as long as body, flagellum shorter than 

 peduncle. Antenna 2 shorter, peduncle not longer than in antenna 1. 

 Gnathopod 2 twice as long as gnathopod 1, 6**» Joint long ovate, tapering, 

 palm the entire length of the inferior margin, straight, flnger (in figure) very 

 long. Peraeopods 3 — 5 not very unequal, 2'^ Joint not much dilated, narrowed 

 below (in figure). üropod 2 considerably shorter than üropod 1, üropod 3 

 a little longer (reaching a little further?) than üropod 1, rami equal. L. 37 mm. 



New Holland. 



