Marshall—Ten Species of Arrenwri. 
149 
a slight indentation in the middle. A lateral view shows that 
the top of the appendage is nearly flat, hut slopes suddenly down 
in the posterior third. Near the rounded side corners are two 
small conical elevations ; these and two other pairs of slight 
mounds, one in front and one hack of the first mentioned, to¬ 
gether with the position of the stout hairs., is seen in fig. 1, 
a and c (H, 2 H, 1 H 3 ). 
The body is rounded, viewed either from above or below, 
with a slight bowing-in in the middle, line and a little conical 
elevation in front of each eye. A lateral view shows that the 
anterior edges of the body are elevated and bear humps and sev¬ 
eral hairs. The genital areas form prominent rolls between 
body and appendage. The dorsal shield is almost circular. 
The color is blue-green with brown streaks and flecks. The 
entire length is 1.06 mm; the width, 0.56 mm; the appendage, 
0.4 mm. 
Neuman’s figures (1879) and Piersig’s (1897) show the ap¬ 
pendage strongly humped up in the anterior part, a feature 
characteristic of the next species. The second joint of the pal¬ 
pus in the specimens examined bears on the inner face a patch 
of short blunt, bristles. In other smaller points., such as the 
shape of the end of the appendage and the humps near the 
eyes, these individuals did not agree with figures of the hy- 
drachnologists mentioned. But their abundance and wide disr 
tribution, together with the fact that there is a general agree¬ 
ment in the form of the body and appendage in a dorsal view, 
seems to justify the identification of these specimens with 
A. globator. A small amount of variation was found in this 
material. 
A. globator feim. The body is broadly oval and the dorsal 
shield has the same form. Very characteristic are the small 
humps on the back as shown in fig. 1, f. In this it disagrees 
with earlier descriptions. The length is 0.8 mm, the width 
0.66 mm. 
Collections extending over several years were made in Lake 
Wingra and the.Yahara Biver, Madison; small pools near Kil- 
bourn; ponds near Big Springs; shallows of Lake Mason near 
Briggsvillei; Goo-se Pond near Jordan Lake, Adams County; 
