318 GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. 
fourths the length of the third and about two-thirds its diameter, 
slightly enlarged at the middle, where it bears, on the under side, a 
group of three long hairs, and upon the upper side two shorter ones. 
At the tip of the segment are a group of three long plumose hairs and 
a stout, curved, concave, acute claw, nearly three times the length of 
the last segment, doubly dentate on both edges. At tip of last segment 
the usually strong, curved bidentate claws, five in number, three of 
equal length, as long as the two last segments of the antenna, and two 
others about half that length. 
‘*Mandible with a row of six dark corneous teeth, more or less bifid, 
the series continued in an irregular cluster of tooth-like spines, and 
terminating in two highly plumose sets. The series of teeth with 
numerous accessory smaller teeth and spines, and two transparent la 
melle—slender, but as long as the teeth themselves—inserted between 
the first and second and second and third series, respectively. The lat- 
ter lamella is recurved and serrate on its concave edge. Basal segment 
of palp longest, the third next, second and fourth sub-equal in length, 
the second as broad as the first. The latter bears at its posterior tip 
three plumose setze of unequal length, in a cluster, and a fourth larger, 
stouter, decurved articulate one, inserted on the outer side of the tip 
of the segment, ‘The second segment has in front a group of three 
slender sete inserted a little behind the tip; and opposite to them 
upon a stout tuberosity another group of three long equal sete, to 
which a fourth stands in the same relation as on the preceding seg- 
ment. On the third segment is a group of five set similar to those 
on the anterior margin of the segment preceding, and, in addition, a 
circlet of six, attached around the posterior and inner margin of the 
end of this segment. At the tip of the palp are three curved claws, 
averaging as long as the two preceding segments together, with some 
slender sete intermixed. The so-called branchial appendage is about 
as long as the basal segment of the palp, and bears four stout plumose 
setee with a small accessory seta in front. 
‘First leg with basal segment columnar, distal portion partially 
separated, without hair or bristle. Second segment cylindrical, its 
surface smooth except for numerous transverse rows of exceedingly 
fine short sets, present also on the two succeeding segments of this 
leg. A stout bristle at anterior distal angle. Third and fourth seg- 
ments nearly equal (the third, however, somewhat the longer), together 
slightly longer than the second, the length of each about twice its 
transverse diameter. The third with a single apical hair at the ante- 
rior angle, and the fourth with but two, one of which is as long as the 
segment itself, and the second about half that length. ‘Terminal seg- 
ment with a very long, slender symmetrically curved, regularly taper- 
