306 
Birge—Notes on Gladocera. 
Pleuroxus nanus, Baird. 
This minute species was found in G-reen lake, at Minocqua- 
and New Lisbon, Wis^, and at Isle Royale. It has been re¬ 
ported from Minnesota by Herrick. 
Pleuroxus hastatus, Sars. 
Plate XIII, Fig. 11. 
A form which, on the whole, seems to me to belong to this- 
species was found in a marshy pool near New Lisbon, Wis. In 
general shape and proportions it resembles P. gracilis , Hud.,, 
and thus is much longer than high. In this respect it differs 
greatly from P. E. Mueller’s figure of P. hastatus , and in less 
degree from the figures and measurements of Hellich, Kurz. 
and Norman and Brady. Hellich is the only author who 
gives dimensions of both height and length. His results are, 
length, 0.55-0.6 mm., hight, 0.32-0. 35 mm. My largest specimens 
measure 0.51 mm. by 0.22 mm. They are nearly as long as those 
of Hellich but only about two-thirds as high. In spite of this 
difference I consider the species the same. The posterior mar¬ 
gin of the shell has the same form as that of the European 
specimens. The'same is true of the size, shape and armature of 
the postabdomen, the length of the beak and the proportions of 
the antennules. 
European authors differ regarding the cilia of the ventral 
edge of the valves. Kurz (74, p. 66) places them in the middle 
only. Hellich (77 p. 102), figures them along the entire ventral 
margin, only slightly shorter at the posterior end. Mueller (’68 
p. 193, P. Ill, f. 25), apparently sees them about like Hellich. 
I find that they almost but not quite disappear at the posterior 
end of the valves, but are much the same as in most species of 
Pleuroxus. 
The marking of the valves in alcoholic material consists of 
striae anteriorly and obscure reticulations behind. In some 
specimens the posterior part of the valves seems obliquely 
striated as in so many of the species of this genus. 
