70 KANSAS ACADEMY OF SCIENCE. 



The present species differs from Leuckartii in having shorter antennse, whose 

 last three joints are subequal; in the size and armature of the apical joint of 

 the fifth foot; in having more slender caudal rami, the relative lengths of whose 

 apical setae are different from those of Leuckartii; in the possession of a very 

 characteristic transverse row of point-like spines on the outer side of the cau- 

 dal ramus; and in lacking a crenulate contour for the dorso-basal margin of 

 the second maxilliped. From abyssorxim, lacustris, and scutifer of Sars, it dif- 

 fers in the armature of the swimming-feet, caudal rami, etc. ; from simplex, 

 Pogg., in the form of the body, first abdominal segment, fifth foot, and cau- 

 dal rami. I have studied it at intervals for over two years, and had given 

 it the manuscript name ^' urbanus," in allusion to its abundance in cities; but 

 it is clearly identical with the recently described C. Thomasi, Forbes. Prof. 

 Forbes has the honor of having published the first new and valid species of 

 Cyclops that has yet been recorded from North America. 



I have most commonly observed C. Thomasi in the water-supplies of Bos- 

 ton and Cambridge, Mass. It is (in winter and spring, at least) easily ob- 

 tainable in any house of either city, greatly outnumbering all other species 

 of Cyclops that pass through the faucets. 



Cyclops magnoctavus, sp. uov. (PI. Ill, figs. 14-23.) 



Cephalothorax subelliptical. None of its segments angulatedat the sides. 

 Its first segment longer than the rest of the thorax plus the first two seg- 

 ments of the abdomen. Its last segment, which is not wider than the first 

 of the abdomen, is set apart from the rest so as to seem like an abdominal 

 segment, and bears at either postero-lateral margin a fringe of delicate hairs. 

 Posterior part of first abdominal segment slightly tapering; anterior part 

 not dilated. Posterior margin of last abdominal segment bearing a pecti- 

 nate fringe. Caudal segments about four times as long as broad, and bearing 

 two superior and four apical setse. Of the apical setae, the first is longer 

 than the spine-like fourth, but shorter than the furca; the second about as 

 long as the last three abdominal segments plus the furca; the third but little 

 shorter than the second. Webs of the second and third composed of deli- 

 cate cilia, which extend well down toward the ramus. Eye large, dark red; 

 deeply divided by a median constriction posteriorly. First antennae com- 

 posed of twelve joints and reaching, when reflexed, beyond the cephalothorax 

 — sometimes nearly to the middle of the first abdominal segment. Their 

 eighth and ninth joints are both longer than either of the last three, the 

 eighth being the longest of all. Each of the last three bears a plain lon- 

 gitudinal ridge. Last joint of second antennae considerably more slender 

 than the others. Labrum with ten to thirteen teeth. The armature of the 

 basal and middle joints of the swimming-feet is like that of C. Thomasi; that 

 of the apical joints is as follows : 



