ENTOMOSTRACA OF MINNESOTA. 107 



C. coronatus are "allgemein bekannt," though adding that Eehberg ad- 

 mits that the yoang of the two species cannot be distinguished until 

 the last moult, which seems to show that the late larvte of C. coronatus 

 are hardly ''allgemein bekannt" even in Earope. Finally Schmeil 

 denies the possibility of sexual precosity with the general statement 

 that ''Auch mir ist trotz der grossten Aufmerksamkeit unter den 

 vielen Tausenden der von mir beobachteten Copepoden noch nicht ein 

 einziges Mai eine solche Larve mit Eiballen zu Gesicht gekommen." 

 To this we can only say that such larv?e have been frequently seen 

 during the last ten years, though only under certain conditions of time 

 and place. It is hoped to furnish conclusive evidence on this head 

 soon if it is really needed. We had supposed that such precosity was 

 now a well-recognized fact. It is to be hoped that careful embryolog- 

 ical and biological studies may be instituted upon the Copepoda. 



Cylcops languidus Sars. 



Plate XVII, Figs. 10, 11. 



Sars '63; Herrick '84; Schmeil '91 and '92; Richard '91. 



This species has not yet been encountered in America, and from 

 the extended discussion of Schmeil we still think there is considerable 

 probability that this form is an illustration of retarded development 

 of some 17-jointed species, perhaps C. hicuspidahts. 



Cephalothorax attenuated anteriorly and posteriorly, narrow. 

 Abdomen slender. Stylets exceeding in length the two preceding 

 segments. Lateral seta at two-thirds the length from the base, two 

 median setre long, two lateral apical setse very short, the outer a ser- 

 rate spine. 



Antennai slightly longer than the first segment, with short setae, 

 16-jointed by the more or less complete fusion of the third and fourth 

 segments. First feet with both rami two-jointed, formula: 



!ex. 3 spines. f ex. 1 seta, 



ap. 2 setoe. Inner ramus < ap. 1 spine, 1 seta, 



in. 3 setfe. ( in. 3 set pe. 



Second foot with a three-jointed outer and two -jointed inner ramus. 

 Formula as follows: 



!ex. 2 spines. ( ex. 1 seta, 



ap. 1 spine, 1 seta. Inner ramus < ap. 1 spine, 1 seta. 



in. 3 setfe. ( in. 4 setae. 



Note. — The following measurements will serve to illustrate the usual proportions of variety 

 ieiiuicornis: Total length, including stylets, 1.4 mm., first segment of thorax 0.5 mm., whole thorax 0.85 

 mm., abdomen 0.52 mm., stylets 0.10 mm., antenns 0.85 mm., last joint of antennre 0.05 mm., longest 

 caudal seta 0.55 mm., inner seta 0.-30 mm. 



The corresponding measurements of C. coronatus are the following: Total length 1.66 mm., first seg- 

 ment 0.67 mm., entire thorax 1.12 mm., abdomen 0.54 mm., stylets 0.07 mm., longest seta 0.6 mm., inner 

 «eta 0.3 mm., antennse 0.95 mm. 



