GAMMARUS PULEX. 
389 
Gammarus pulex , 
Gammarus aquations. 
Gammarus Fossarum. 
Crevette des ruisseaux. 
Gammarus Jiuviatilis. 
Desmarest, Cons. Crust, p. 266, tab. 45, fig. 8. 
Zenker, Comment, de Gamm. pul. fig. a c and 
details. Gervais, Ann. Sci. Nat. 2 ser. iv. 
p. 128. Hosius, Dissert, de Gammari spec, 
p. 19 ; and in Wiegm. Arcbiv. 1850. i. p. 233. 
Bgrgersdyk, Annot. de Crust, indig. p. 4. 
Milne Edwards, in Cuvier, Regne An. edit. 
Crocbard, pi. 60, fig. 1. Milne Edwards, Hist. 
Nat. Crust, t. iii. p. 48 ? ? Latreille, Hist. 
Nat. Ins. &c. vi. p. 316? Gen. Crust. Ins. i. 
p. 58 ? Leach, Edin. Ency. vii. p. 402, 432 
(not of Fabricius). Bruzelius, Stand. Ampb. 
Gam. p. 54. Liljeborg, Kongl. Yetensk. Akad. 
Hand]. 1853, p. 449. 
Leach, Linn. Trans, xi. p. 359. Suppl. Encyc. 
Brit. i. p. 425. Samouelle, Ent. Comp. p. 103. 
Koch, Deutscbl. Crust. Myr. u. Aracb. h. 5, No. 1 ; 
and Panz. Ins. Germ. Suppl. h. 138, No. 1. 
Geoefroy, Hist, des Ins. ii. p. 667, pi. xxi. fig. 6 ? 
Milne Edwards, Ann. Sci. Nat. t. xx. p. 368. 
Zaddach, Prodr. Syn. Crust. Pruss. p. 6 (not of 
Ray nor Rosel). 
The present species bears so near a resemblance to 
G. locusta, in everything except colour and habitat, that 
it requires the closest observation to distinguish the two 
species. In all the marine species the fasciculi of spines 
upon the dorsal surface of the caudal segments are short 
and stiff, whilst in this fresh -w r ater species they are 
mixed with others of a more slender hair-like character. 
The eyes also are formed of minute black dots, and 
rounder, though still reniform. The superior antennae 
have the peduncle extending only to the extremity of 
the penultimate joint of the peduncle of the lower pair; 
the secondary appendage is very slender, shorter than in 
G. locusta , and composed of only three or four articuli. 
The inferior antennas are rather shorter than the su- 
perior, they have the olfactory organ largely developed, 
and the flagellum in the male is very robust. The first 
two pairs of legs are subequal ; the hands are nearly 
of the same size, but the second pair have the palm less 
