156 Illinois State Laboratory of Natural History. 



from other localities, and no tendency toward constancy in 

 number of eggs for the same locality was made out. 



The furcal rami in both sexes are hairy within, a point not 

 mentioned in the original description, although the rami are 

 so figured. All the specimens which I examined from the 

 various localities had this characteristic, although individuals 

 varied slightly in this particular. 



As mentioned under the description of D. pallidus, D. sicl- 

 loidcs was the most abundant form found at Havana. It also 

 formed the greater part of the material from Spirit Lake, 

 Iowa, which was kindly loaned me by Prof. L. S. Ross, of 

 Drake University, Iowa. 



The individuals taken from the Illinois River at Havana, 

 Illinois, in July and August, 1896, were all of an indefinite 

 color about like opalescent glass. The egg-sac in these was 

 blue, and there was a small pink spot near the eyes and just 

 behind them. These were the only specimens of slcllolcles 

 which I had opportunity to examine alive. 



Diaptomus minutus Lilljeborg. (PI. XXX., Fig. 5-8.) 



Diaptomus minutus, de Guerne et Richard, '89b, p. 50, PL I., Fig. 5, 



6,14; PI. III., Fig. 25. 

 Diaptomus minutus, Marsh, '93, p. 199, PI. IV., Fig. 1-3. 

 Diaptomus minutus, Marsh, '95, p. S, Pi. VII., Fig. 3. 



"Among the smallest of the genus. Body slender, widest 

 in front of the middle of the cephalothorax and at the pos- 

 terior part of the head. Fourth and fifth segments commonly 

 confluent above, sometimes in the adult specimen separated 

 by a suture; the lateral lobes, seen from above, short and 

 rounded, and provided with minute mucros. First abdomi- 

 nal segment of the female (PI. XXX., Fig. 8) about as long 

 as the remainder of the abdomen; rather dilated at its an- 

 terior part and rounded laterally ; furnished with very minute 

 spines. Second segment very short, third segment much 

 longer, and these segments indistinctly joined. Furcal rami 

 about twice as long as broad. Furcal setae unusually long. 



"First pair of antennae of female somewhat surpass the 

 furca; composed of 25 segments. Antepenultimate article of 



