454 Phreatogammarus, Ommatogammams 



1. P. fragilis (Chilton) 1882 Gammarus f., Chilton in: N. Zealand J. Sei.' 

 V. 1 p.44 I 1882 G. f., Chilton in: Tr. N. Zealand Inst., v. 14 p. 179 t. 9 f. 11—18 \ 1889 

 G. f., Moniez in: Rev. biol. Noi-d France, v. 1 p. 253 | 1890 G. f., Wrzeäniowski in: Z. 

 wiss. Zool., V. 50 p. 611, 698 | 1894 G. f., Chilton in: Tr. Linn. Soc. London, scr. 2 v.6 

 p. 227 t. 21 f. 1—25 I 1899 Phreatogammarus f., T. Stebbing in: Tr. Linn. Soc. London, 

 ser. 2 V.7 p. 427 | 1893 Gammarus fluviatilis (part.), A. Della Valle in: F. Fl. Neapel, 

 V.20 p. 763. 



Body rather slender; pleon segraents 4 — 6 each with 4 or 5 dorsal long 

 spine-like setae. Head without rostrum, lateral augles broadly roimded, little 

 produced. Side-plates rather shallow. Pleon segraents 2 and 3 with postero- 

 lateral angles blunt Antenna 1 subequal to body, 1^* Joint long, not quite as 

 long as 2** and 3"^ combined, flagellum many-joiuted, more than twice as long as 

 peduncle, accessory flagellum 6 — 9-jointed. Antenna 2 more than half as longas 

 antenna 1, ultimate Joint of peduncle slightly longer than penuftimate, flagellum 

 subequal to peduncle, about 20-jointed. Upper lip nearly semicircular, rauch 

 broader than deep. Lower lip without inner lobes. Mandible, 1^*^ Joint of palp 

 nearly half as long as 2^, distally a little widened. Gnathopods 1 and 2 in 9 rather 

 large, 6^^'^ Joint ovate, palm very oblique, finger long, curved. Peraeopods 1 

 and 2 slender. Peraeopods 3 — ö long, 2^ Joint not very widc, naiTOwing 

 downward, finger small. Peraeopods 4 and 5 with 6*^ Joint much the longest. 

 Peraeopod 5 nearly as long as body. üropod 3 extending much beyond the 

 others, the rami about twice as long as peduncle. scarcely tapering, each with 5 

 groups.of 3 spiues and an apical group of 6 or 7 spines. Telson short, the 

 lobes almost rectangular, each with 4 or 5 spines on the obtusely truncate apex 

 and 2 or 3 a little above on outer margin. Colour white, semiti'ansparent. 

 L. reacliing 15 mm. 



New Zealand. Wells. 



41. Gen. Ommatogammarus Stebb. 



1899 Ommatogammarus, T. Stebbing iu: Tr. Linn. Soc. London, ser. 2 v.l p. 427. 



Near to Gammarus (p. 460). Dorsal spines only on pleon segments 

 4 — 6. fjyes in*egular, with indented outline (Fig. 86). Antenna 1 the longer, 

 but with peduncle usually shorter than that of antenna 2; accessory flagellum 

 of more than 1 Joint (Fig. 86). Upper lip narrowed to a rounded apex. 

 Lower lip, inner lobes rudimentary. Mandible, 3^ Joint of palp not very 

 elongate. Maxilla 1, inner plate fringed with numerous setae, outer canying 

 11 spines, 2'^ Joint of palp. with about 10 spine-teeth on one maxilla and 

 Short spines on the other. Maxillipeds, outer plates reaching far along 

 2^ Joint of palp, spine-teeth and setae numerous. Gnathopod 1, 6*^ Joint 

 not smaller than that of gnathopod 2. Uropod 3, outer ramus about twice 

 as long as inner, with simple setae 011 its outer margiir, inner ramus with 

 feathered setae on both margins. Telson cleft to the base. 



4 species. 



Sj'nopsis of species : 



( Dorsal margin oi' head abruptly bent downward — 2. 



1 \ Dorsal margin of head not abruptly bent down- 



\ ward — 3. 



J Eyes with hind margin acutely indentured ... 1. O. albinus .... p. 455 



\ Eyes with hind margin obtusely lobed 2. O. flavus . . . . p. 455 



/ Eyes broad 3. O. earneolus . . . p. 456 



1 Eyes narrow 4. O. amethystinus . p. 456 



