45 
been found on the Swedish side of the Kattegat (Lilljeborg). In 
the specimens from Randers Fjord (fig. 6) the cephalon has the 
same form as in G.puleæ, 
and also the 2. jointof p5, 
which is of great system- 
atical importance, is much 
narrower than shown by 
Sars and of totally the 
Same shape as in G. pulex ; 
in all other regards the 
specimens correspond very 
well with Sars' descrip- 
tion and figures. 
It is thus probable that this species is merely a brackish water 
variety of G. pulex.  Localities see p. 50. 
Fig. 6. Gammarus Duebenii id. 17 mm. 
Gammarus pulex L. 
Gammarus pulex Sars, Account, vol. 1, 1895, p. 503, Pl. 177, fig. 2. 
Er —  Stebbing, Amphip., Tierreich 1906, p. 474 (lit. 
and syn.). 
SEE: locusta var. B. Hoek, I. c. 1889, p. 214, Pl. 10, fig.12, 12!. 
Ems pulex Sexton | cc. IOT2 D 657, 
== BEN ms]. 1013 p. 90, PE 4, fig: I 
DE — Knut Dahl, En studie over grundaatens eller mat- 
floens (Gammarus pulex) biologi og utbredelse i 
Norge; Norsk Jæger- og Fiskeriforenings tids- 
skrift 1915. 
Gammarus pulex is found in all the streams in the vicinity 
Randers; 4 spec. were also found in the part of the fjord 
called ,Snævringen", —< 1 %oo salinity, and 4 spec. were taken off 
Tjæreby about 2 miles E. of Randers, salinity < 0.5 Yo (perhaps 
<3%/00). Thus it seems that the species cannot live in water of 
salinity greater than 1/00 (3%00?). In the innermost parts of the 
ford at Randers Gammarus is not found, probably because the 
Water is not clean. Localities see p. 50. 
The most important characters are (Sars, Account p. 503—504): 
o 
== 
