TROMBIDIIDAE OF MINNESOTA 125 
sessile. Dorsal groove expanded at the posterior end. Palpi rather 
slender, segment II twice as long as wide at widest part, segment II] 
as long as wide, one-third as long as II, segment IV as long as III, 
two claws at the tip, the inner smaller. Thumb almost cylindrical, 
slightly clavate, longer than segment IV. On the outer side of seg- 
ment IV are three heavy spines at the base of the thumb, and near 
the base of the claw two long branched hairs projecting dorsally ; on the 
inner side are two oblique rows of six or seven stout hairs each, legs 
slender, tarsi I not swollen, a little more than three times as long as 
wide, claws very long and slender, those of tarsi I much smaller than 
those on the other tarsi. 
One specimen was taken in a cultivated garden in Minneapolis, 
along with Serico. scabrum on May 22, 1917, another at Fort Snelling 
in low lands, along with Ew. locustarum and Serico. scabrum. 
This species might easily be confused with Serico. scabrum were 
it not for the white markings. Its habits also seem to be the same. 
In the laboratory it was impossible to find any food which it would 
take. On one specimen the white markings were more extensive than 
described above, the white triangles extended along the margin of the 
abdomen nearly to a transverse white band at the rear margin. 
Microtrombidium nopal-rubrum, n.sp. 
Adult female. Color, nopal red, lighter on the under side and legs. 
Size 1.50 mm long by 1 mm wide. Body flattened and oval in outline, 
wider in front, anterior edge deeply emarginate, posterior end rounded, 
no constriction at the middle. Entire dorsal surface sunken, with 
two deep anterior transverse grooves, two shallow median transverse 
grooves, present or absent, and a large, shallow, posterior, convex area. 
Ventral surface with genital pore opposite coxae [V. Anus just pos- 
terior to genital pore. Body covered thickly with peculiar stout 
branched hairs expanded at the top and turned backward. Muingled 
with these, especially near margins of the body are short globose hairs. 
Cephalothorax as wide as long, set into a deep emargination of the 
abdomen so that it is entirely exposed. Clavate hairs on cephalo- 
thorax, with ends turned forward. Eyes sessile. Dorsal groove ex- 
panded on the posterior end. Palpi stout, and curved, segment II two 
thirds as wide as long, segment III as wide as long, segment IV a third 
longer than III, two stout terminal claws, the inner one smaller, thumb 
stout and cylindrical, as long as segment IV. Segment IV has on the 
inner surface a dorsal comb of stout hairs, also a double row of stout 
hairs parallel to the dorsal edge. On the outer surface are clavate 
hairs like those on the body. All other hairs are slender and barbed. 
