f)03 



RemarJcs. — The short description given by Prof. Lilljeborg of his 

 G. Duebeni does not leave any doubt of its identity with the species here 

 treated of. It is likewise quite certain, that the form recorded by Mr. Nor- 

 man as G. campijJops is this species, and not that of Leach. Mr. Hoek 

 describes this form as a variety of G. locusta. Though very nearly allied to 

 the 3 preceding species, this form may, on a closer examination, be easily 

 distinguished from any of them. As the moist conspicuous feature may be 

 named the dense supply of slender hairs clothing the dorsal face of the 

 urosome, as also the 3 posterior pairs of pereiopoda, the last pair of uropoda 

 and the telson. From G. locusta to which it comes nearest, it is moreover 

 at once distinguished by the very different form of the lateral corners of 

 the cephalon, which somewhat resemble those of G. marinus. 



Occurrence. — I have met with this species very abundantly in 

 brackish pools among the shore-rocks, lying considerably above high-vrater-mark. 

 It is here often associated with true fresh-water forms, as Daphnia magna 

 and D. pulex, and with the brackish-water forms: Tigrioptis fuhus, Temora velox, 

 and Cypris salina. Occasionally it is also found at the beach, beneath 

 stones or decaying algae; but I have never observed it freely in the sea. 



Distribution. — Kattegat (Lilljeborg), British Isles (Norman), the 

 Dutch coast (Hoek), warm springs of south Greenland (Copenhagen Museum). 



12. Gammarus pulex, de Geer. 



(PI. 177, fig. 2). 



Squillc 2>ouce, de Geer.Me moires pour servir h I'histoire des Insectes, T. VII, p. 526, PI. 33. 



Syn. Gamroarus fluviatilis, M. Edw. 



J — lacustris, G. O. Sars. 



> — neglectus, G. O. Sars. 



J — locusta, var. B, Hoek. 



Form of body about as in the other species. Cephalon with the 

 lateral corners transversely truncated, but somewhat less broad than in 

 G. Duebeni, and defined below by a very deep sinus. Coxal plates of 

 moderate size, and but little differing in shape from those in the said species. 

 Last pair of epimeral plates of metasome but very little produced at the 

 lateral corners. Segments of urosome evenly vaulted above, each with 2 

 small dorsal spinules and but a single lateral one. Eyes very small, and 

 oval of form, pigment black. Superior antennaj nearly half as long as the 

 body, 1st joint of the peduncle shorter than the other 2 combined, flagellum 



