246 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
between the first and second and the second and third series} respectively. The latter 
lamella is recurved and serrate on its concave edge. Basal segment of the palp long- 
est, the third next, second and fourth subequal in length, the second as broad as the 
first. The latter bears at its posterior tip three plumose set® 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 set® inserted a little behind the tip ; and opposite to them upon a stout tuber- 
osity another group of three long equal set®, to which a fourth stands in the same 
relation as on the preceding segment. 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 set® intermixed. The so-called 
branchial appendage is about as long as the basal segment of the palp, and bears four 
stout plumose set® 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 surfaces 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 anterior angle, and the fourth with but two, one of 
which is as long as the segment itself, and the second about half that length. Termi- 
nal segment with a very long, slender, symmetrically curved, regularly tapering claw, 
with two short soft set® springing from its base. The entire claw somewhat longer 
than the last three segments conjointly. 
Caudal rami long and slender, slightly sinuate, the transverse diameter of each not 
more than one-twentieth its length; the basal fifth, however, considerably thickened. 
Rami smooth, except posteriorly, where the margin is closely set with stout, short 
spines, lengthening toward the distal end of the ramus. Terminal claw slightly 
curved at tip, contained two and a half times in the length of its ramus. Subterminal 
claw nearly two-thirds the length of the terminal, also slightly curved. Claw-like seta 
almost immediately above the latter, more slender, but two-thirds its length. Besides 
the above, a short slender seta springs from in front of the base of the terminal claw. 
The first and last segments of the second pair of legs subequal, each two-thirds 
the length of the second; basal segment straight, its length five times its width, with 
three slender set®, one borne upon the middle of its exterior side, and two near the 
apex, opposite each other. Second segment slightly curved, with a single slender seta 
near the apex, on its outer margin. Third segment with two terminal set®, one nearly 
straight, and claw-like, about three-fourths the length of its segment, and the other 
curved and blunt. 
This species may be the same as C. grandis Chambers*, which it certainly seems to 
resemble closely, but from which it differs, if I may judge from the published brief 
description and rude figures, in color, surface, form, arrangement of antennal set®, and 
other minor details. 
Yellowstone River, Yellowstone Park, Wyoming. 
*“ New Entomostraca from Colorado,” in Bull. U.S. Geol. and Geogr. Surv., vol. in, No. 1, p. 151. 
