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 setae 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 setae inserted a little behind the tip; and opposite to them upon a stout tuber- 

 osity another group of three long equal sette, to which a fourth stands in the same 

 relation as on the preceding segment. On the third segment is a group of five setae 

 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 setae intermixed. The so-called 

 branchial appendage is about as long as the basal segment of the palp, and bears four 

 stout plumose setae with a small accessory seta hi 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 setie, 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 setae springing from its base. The entire claw somewhat longer 

 than the last three segments conjointly. 



Caudal raini long and slender, slightly sinuate, the transverse diameter of each not 

 more than one-twentieth its length; the basal fifth, however, considerably thickened. 

 Kami 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. Subterininal 

 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 subeqnal, each two-thirds 

 the length of the second; basal segment straight, its length five times its width, with 

 three slender seta}, 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 setae, 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 auteunal setoa, and 

 other minor details. 



Yellowstone Eiver, Yellowstone Park, Wyoming. 



*" New Entomostraca from Colorado," in Bull. TT.S. Gool. anil Geogr. Surv., vol. in, No. 1, p. 151. 



