248 BULLETIN OF THE UNITED STATES PISH COMMISSION. 



The abdominal segments are as long as the cephalothoracic segments two to five 

 taken together, and the fnrca is as long as the last three segments. The first segment 

 of the abdomen 'is broadest in front, where its width is nearly as great as its length. 

 The second is as broad as long, the third and fourth equal, the fifth a little shorter, 

 the last with a row of fine spiiiules around the base of the ranii. 



The width of each rainus is contained nearly eight times in its length. Besides 

 the lateral spine situated a little before the posterior third of the ramus there is a 

 cluster of two or three minute spines at its anterior fourth. The outer and inner 

 terminal setae are reduced to short subequal spines about twice as long as the ramus 

 is wide. The other setae are slender, plumose, the inner nearly twice as long as the 

 outer of each pair. 



The antennae are rather stout and short, seventeen-jointed, reaching to the end 

 of the second segment. They are without special structures or appendages. 



The last segments of the thoracic legs aie armed as follows: 



First pair : outer ramus, one spine and two setie at tip, two setre within, and one 

 spine without; inner ramus, one spine and one seta at tip, three setae within, and one 

 seta without. 



Second pair: outer ramus, one spine and one seta at tip, three setce within, and 

 two spines without; inner ramus, one spine and one seta at tip, three seca3 within, and 

 one seta without. 



Third pair: outer ramus, two spines and one seta at tip (one spine twice as long 

 as the other), three setae within, and one spine without; inner ramus, one spine and 

 one seta at tip, three setie within, and one seta without. 



Fourth pair: outer ramus, two spines and one seta at tip (one spine double the 

 length of the other), three setae within, and one spine without; inner ramus, two spines 

 at tip (one double the length of the other), two setae within, and one seta without. 



The fifth pair is two-jointed, the basal joint broad, Quadrate, with a seta at its 

 outer angle; the second cylindrical, with one long and one short seta at tip. 



Length, without setae, 1.34 millimeters. 



Described from females only. 



Cyclops capilliferus, n. sp. (Plate XL, Figs. 14-17, and Plate XLI, Fig. 18.) 



This is a symmetrical, compact Cyclops, with the cephalothorax closely articulated, 

 widest at the middle, and the sides regularly convex, with the abdomen narrow and 

 slender, with three well-developed caudal setie, and sixteen-jointed antenna bearing 

 several very long setie. 



The abdomen, with caudal furca, is contained a little less than twice in the ceph- 

 alothorax, and the breadth of the latter is just half its length. First segment very 

 long, five times the length of the second ; second and third equal ; the fourth very 

 short, on the median line semicircularly excavate behind. The abdominal segments 

 in the female diminish regularly in length from first to last. The caudal rarni are 

 twice the length of the last segment and one-fourth as broad as long. The lateral seta 

 is placed a trifle beyond the middle of the ramus; the outer terminal seta is a short 

 naked spine; the other three are well developed and plumose. The inner and outer 

 of these three are of nearly equal length, the latter a little the longer, the middle one 

 much the longest one of the group. 



