ENTOMOSTRACA OF MINNESOTA. 295 



tory organs symmetrica], and of moderate size." (Brady and Norman.) 

 It is thought that the following modification of Wenzel Yavra's 

 key will serve to differentiate the genera. 



KEY TO THE FAMILY CYPRIDIDJE. 



I. The second foot terminates with a cylindrical joint that bears two 

 backwardly directed setce. 



A. The second foot of the female and the male six-jointed. No 



branchial plate attached to the second maxillae. Notodroiuas, 295 



B. The second foot of the female five-jointed and of the male 



six-jointed. The second maxilla bears a branchial plate. 



a. The branchial plate is feebly developed in the form of two 



pectinated bristles. 



* The eye is developed Caiiclona, 298 



** The eye is absent. . . . . *Tyi>lilocypris. 



b. The branchial plate is developed in the form of three pec- 



tinated bristles *Candonopsis. 



c. The branchial plate is in the form of six pectinated bristles. 



* The palp of the second maxilla is rudimentary. . *Ilyocyi)ris» 

 ** The palp of the second maxilla is normally developed. 



t The terminal joint of the second foot is as long as 



one-third of the fourth joint. . . . Cypria, 304 



tt The terminal joint of the second foot is as long as 



two-thirds of the fourth joint. . . Cyclocypris, 310 

 II. The second foot terminates in a beak-shaped joint that bears one 

 backwardly directed claw. 



A. Caudal rami are rudimentary Cypridopsis, 312 



B. Caudal rami are cylindrical with two terminal claws. 



* Natatory setse of the antennae short. 



t These sette not reaching to the tips of the terminal claws. 



Erpetocypris, 315 

 tt These setae not reaching to the base of the terminal claws. *Scottia. 

 ** Natatory setse of the antennse long, reaching to or beyond 

 the tips of the terminal claws. 



t Parthenogenetic Cypris, 319 



tt Sexual Cyprinotu8, 329 



(*Not noticed in the text.) 



In the above table an attempt has been made to tabulate all known 

 freshwater genera of the Cyprididce. The genus Steywcypris Sars has 

 been omitted because the data at my disposal do not seem to warrant 

 its separation from the genus Erpetocypris Brady and Norman. Of 

 the twelve genera here mentioned, nine have been found in America. 



GENUS NOTODROMAS Lilljeborg. 1853. 



In shape the shell of the male is quite different from that of the 

 female. 



The antennules are seven jointed. 



