28 Bulletin Wisconsin Natural History Society [Vol. 13, No. 1 
The first pair of swimming feet bear only plumose setae and the next 
three pairs bear spines on the outer margin of the exopodite as in the female 
(fig. 5). The first, third and fourth pairs of feet are symmetrical, only 
the second and fifth pairs are asymmetrical (fig. 4, A,; fig. 6). 
Fig. 4. Heterocope septentrionalis n. sp. A, Fifth Feet of the Male. 
A1-A4, Showing Variations in Left Foot of the Male. B , Fifth Foot 
of the Female; C, Abdomen of Female; D, Genital Segment of Female, 
E , Genital Plate of Female, F, Abdomen of Male. 
Second feet. — The first joint of the right exopodite (fig. 6 , A) is some- 
what shorter and broader than the corresponding joint of the left foot 
(fig. 6, B) and the spine of the right joint is slightly longer and distinctly 
stouter than that on the left. The second joint of the right exopodite is 
slightly smaller than that of the left side and bears a distinctly longer spine. 
The last joints of these exopodites are similar in size and form, the right 
joint being a little broader than the left in some individuals. The long 
