292 Birge — Notes on Cladocera. 



length and have two anterior sense-hairs. The first leg lacks 

 the flagellum. 



The following differences are found: 



M rectirostris. M. propinqua. M. affinis. 



Ephippium, smooth in center, smooth in center, reticulate. 



Terminal claw, pectinate, not pectinate, pectinate. 



Valve, smooth or faintly reticulate, anastomosing str.'ae, anastomosing striae- 



Antenna, smooth, villous, villous. 



Male antennule, bend close to middle, bend close to middle, bend near head. 



Terminal hooks, six, three, four. 



Zoosperm. radiate, spherical, spherical. 



In view of these differences I have decided to consider this a 

 separate species. It is certainly as distinct as is M. propinqua 

 and as species of far-distant countries are so nearly allied it 

 becomes necessary to mark every difference in order that 

 students may note the extent of variation. No doubt later re- 

 visers of the genus will reduce the number of species. 



This species is of common occurrence in Wisconsin and has 

 probably been found elsewhere in the United States. The de- 

 scriptions given by Herrick and others are not in sufficient 

 detail to enable one to decide whether the form found was this 

 or the regular 31. rectirostris. 



The species occurs in muddy pools and similar localities after 

 the regular custom of Moina. 



Moina flagellata, Hudendorff, variety. 



Plate X, Figs. 2, 4, 6, 9, 10, 11. 



This species appeared in a muddy pool in Madison in July, 1892,. 

 and in June, 1893. The specimens included males and females 

 with ephippia. These specimens closely resemble the elaborate 

 description given by G-ruber and Weismann for this species 

 under the name of M. paradoxa ('77, pp. 82, ff). There are some 

 differences which would warrant the separation of the American 

 form as a distinct variety if they should be found constant in 

 specimens from other localities. These are: 1. The shell is 

 marked with striae, much as in M. affinis, Birge. These can be 

 easily seen in clean individuals even under the coverglass. 



