Daphnia longiremis. 
299 
a small one may easily be present. Sars now (’90, p. 10, 33.) 
regards the species as a variety of D. galeata. I do not follow 
him in this as my material does not warrant the change. In¬ 
deed I find it difficult to understand his later classification of 
the species D. galeata and D. hyalina with their numerous 
varieties. 
Daphnia longiremis, Sars. 
Plate XI, Figs. 4, 5, 7, 8, 9, 10, 11, 12. 
There is only one description of European specimens of this 
species, that of Sars (’62, p. 148.). Schoedler (’66, p. 30.) 
and Eyimann (’86, p. 42.) both take their descriptions from 
Sars’ original account, as also does Herrick (’84, p. 73.). Sars 
in his later paper makes this species a variety of D. cristata 
(’90, p. 10, 35.). 
Sars’ account is silent on some points of structure which are 
quite conspicuous in my specimens, so that I am not sure that 
they belong to Sars’ species, but as they agree in general struc¬ 
ture and especially in the great length of the antennas I prefer to 
keep them here rather then to make a new species on doubtful 
grounds. 
The specimens examined are pellucid and greatly compressed 
laterally. The valves as seen from the side are broadly ellip¬ 
tical. The spine is long, very slender, and inserted a little 
above the middle of the valves and is directed somewhat 
dorsally. It is armed on the side with small spinules. These 
extend along the ventral margin of the shell but do not go be¬ 
yond the base of the spine on the dorsal side. The reticulation 
of the valves is very indistinct, almost invisible in alcoholic 
specimens. 
The head is small, evenly rounded in front; the ventral mar¬ 
gin straight, slightly convex or slightly concave. The rostrum 
varies greatly, being in some examples a long, pointed nose, and 
in others practically absent. The figures give a good idea of the 
range of variation. 
The antennae are very long and slender. When reflexed they 
extend nearly to the base of the spine but never quite reach it. 
