480 Wisconsin Academy of Sciences, Arts, and Letters. 
distal end. The first segment of the exopodite is small and 
quadrate. The second segment has about the same width as 
the first, and its length is about that of the second basal seg 
ment. Its outer margin is convex and its inner sinuous. The 
lateral spine is situated at about two-thirds the length of the 
segment, and is commonly straight and rather weak. The ter¬ 
minal hook is falciform with a regular curve, is denticulate on 
the inner margin, and is about equal in length to the second 
segment of the exopodite. The right endopodite is short and 
stout, much shorter than the first segment of the exopodite, 
setose at tip. Frequently the joint between it and the second 
basal segment disappears, and the endopodite appears simply 
as a prolongation of the inner distal angle of the second basal 
segment. 
The left fifth foot reaches to the end of the second basal seg¬ 
ment of the right foot. The second basal segment is quadrate, 
its inner margin strongly convex. The lateral hair is situated 
at the outer distal angle, is stout and plumose. The first 
segment of the exopodite is small and trapezoidal, widest at 
the base. The second segment is twice the length of the first, 
armed on its inner surface with a hemispherical setose pad. 
It terminates in two curved spines forming a foreipate struct¬ 
ure. The inner spine is movable, bears a small tubercle on the 
inner side of its base, and is setose. The endopodite is about 
three times as long as broad, longer than the first segment of 
the exopodite, and is setose at tip. 
Length of female, 1.4 to 2.12 mm. Length of male, 1 to 
2 mm. (Schacht). 
Occurs only in the early spring in stagnant pools. It is 
found quite generally in the Mississippi valley. It has been 
found as far east as Hew York, as far north as Wisconsin and 
Minnesota, as far west as Nebraska, and as far south as Ala¬ 
bama. 
D. sanguineus is a very variable species. Some of these 
variations have been discussed in some detail by Schacht. The 
variations do not seem to be so great, however, as necessarily 
to raise any question as to specific identity. Inasmuch as there 
