646 On some Entomostraca from Lake Michigan [August, 



The thoracis 



: segments corresponding to the two la-^t pairs of legs are not distinct, 









complete suture. The body is .065 in. long (without caudal setae) by 





tdepth " 







lyclops, herea 



fter to be described, almost the entire first food of the whitefish. I 



ave not fouiv 



I it anywhere outside of Like Michigan, but there it occurs in im- 



2. Diaptomus hptopus, ftp. nov. (PI. vm Figs. 17-19.) 

 This species resembles the foregoing in general appearance, but may be easily dis- 

 tinguished by the relative robustness of the antenn.e and the shortness of their hairs 

 and spines, by the width and shortness of the rami of the furca (the width being a 



and the different shape and proportions of the fifth pair. 



An average male measures .07 in. in length by .015 in. in depth. The cephalo- 

 thorax is a little the widest before the middle, wish angles rounded and terminating 

 in a single acute spine. The second segment of the female abdomen is very short. 

 The antenna: reach to the tip of the furca, and the antepenultimate segment of the 



the outer is dentate externally and plumose within, while the short spine at its base 

 is dentate on both margins. The outer cd.-e of this ramus is hinged with long deli- 

 cate pubescence. On all the swim.nin ■ fee. the terminal seta is dentate externally. 

 The characters of the liftb pair „f legs of male and female are sufficiently shown by 



