STATE GEOLOGIST. 231 



riety induced by alpine habitat as suggested by Brady, occurring as a 

 **post imago" form with the ordinary type. Glaus' description of 

 Cyclops spinidosus suggests that this form may be the basis of his 

 species though the form of the male antenna is different from any 

 yet seen. Cyclops minutus, Glaus, is most certainly the youug of some 

 Cyclops, as is indicated both by the description and figures in Die Frei- 

 lehenden Copepoden. Though placed among the twelve -jointed forms the 

 antennae are eleven-jointed. The fact that the females may have had 

 egg sacs is no proof of their maturity as I have seen undoubted larval 

 forms of serulJatus with the sacs. Moreover two-jointed branches of 

 sivimming fest is a larval character. This is a cosmopolitan and very 

 abundant species, occurring in almost all pools and lakes about Min- 

 neapolis. The form and structure of the stylets, antennae and feet 

 make it an easily recognized species. 



CYCLOPS FLUVIATILIS, Sp. UOV. 



(Plate yil, figs. 1-9.) 



A very small and distinct species of the section with 12-jointed an- 

 tennae was found in an estuary of the Mississippi river, (also later in 

 L. Minnetonka) with the following characters: — 



Body elongated; thorax very long; abdomen slender; stylets about 

 as long or longer than last abdominal segment ; setae all very short, not 

 pectinate; lateral and dorsal setae ver}'- small; outer one spine -like 

 short and stout, two middle short, inner one very small and incon- 

 spicuous: antennae reaching nearly to the base of abdomen; formula, 



— — ^^ — — ; the three joints following the six 



basal are much elongated while the terminal ones are but moderateh' 

 so, a character which is peculiar to this species; terminal segment 

 slightly but evidently hinged, and together with pair preceding some- 

 what curved; feet with the terminal spines strongly toothed; fifth 

 foot very small, one- jointed, bearing three small setae; operculum 

 vulvae heart-shaped; egg sacs subquadrangular; eggs large; abdomen 

 in the young much elongated; color deep indigo, length j Jo cm. 



CYCLOPS ADOLESCENS, Sp. UOV. 



(Plate VI, figs. 16-20.) 



The form figured under the above name seems closely allied to C 

 affinis, Sars, from which it differs chiefly in the arrangement of the 

 joints of antennae. 



