154 Illinois State Laboratory of Natural History. 



(Herrick and Turner, '95, p. 73) that "according to Richard's 

 drawing the spines are dentate," I judge that he also found 

 them smooth, since his own figures show them to be so. 



This species was first found in 1888 at Portland, Oregon, 

 by Trybom, and described in 1889 byLilljeborg in de Guerne 

 and Richard's "Revision." Marsh says ('93) that it is the most 

 common form in central Wisconsin, being found quite gener- 

 ally in the shallower lakes, and that it occurs in the Great 

 Lakes, but not abundantly ('95). Herrick (Herrick and 

 Turner, '95) says that within the limits of Minnesota it had 

 been found only in Lake Minnetonka. I can now add Lake 

 Calhoun, Minn., and Sand Lake in northern Illinois. 



Diaptomus siciloides Lilljeborg. 



Diaptomus siciloides. tie Guerne et Richard, 'S9b, p. 54, PI. I., Fig. 



7,8,28,32. 

 Maptomus siciloides, Herrick and Turner, '95, p. 69, PI. VIII.. Fig. 10. 



"Among the smaller of this genus. The general form of the 

 body agrees almost exactly with that of D. gracilis Sars. 

 Cephalothorax slender, widest at the middle. The last two 

 thoracic segments confluent above. Lateral lobes of the 

 last one, seen from above, short and rounded, with rather 

 large mucros. First abdominal segment long, fully as long 

 as the remaining part of the abdomen (without the setae) ; 

 with distinct lateral processes at the anterior part, acuminate 

 and bending forward slightly. Furcal rami short, but fully 

 one and a half times as long as broad. 



" First pair of antennae of the female, reflexed, surpass the 

 furca but do not reach the tips of the furcal setae ; composed 

 of 25 articles. Antepenultimate article of the prehensile 

 antenna of the male provided with a rather long hook-like 

 process reaching about to the middle of the penultimate 

 article. 



"Fifth pair of feet in the female small but rather thick; 

 outer ramus biarticulate, hook-like process of second seg- 

 ment slightly curved, and almost equal to the first segment ; 

 the inner margin partly ciliate. Inner ramus simple, slightly 

 longer than the first segment of the outer ramus ; with a 

 small seta, slightly hairy at the apex. 



