470 Illinois State Lahoratory of Natural History. 



Length, .60-.70 ram., height, ,35 mm., width, .38- 

 .45 mm. 



Seen from above, the shell is broadly ovate, widest 

 back of the middle. Three characteristic darker bands 

 varying from dark brown to green extend down each 

 side from a longitudinal dorsal band. These bands to- 

 gether with its oblong spheroidal form and plump 

 appearance can hardly fail to identify the species. 



The caudal rami are rudimentary, the terminal part 

 being produced into a long slender stylet which is some- 

 what longer than the ramus. 



This species is ubiquitous, and I have yet to know of 

 a pond or stream which it has not made its home. It 

 is seemingly always present in aquaria, and appears to 

 play the role of scavenger, thriving in situations to 

 which other Ostracoda seem to be totally unadapted. 

 Viewed wuth a low power these creatures present a very 

 pretty appearance as they rapidly swim about, the 

 banded shell at once attracting attention. 



It would seem that its great adaptability to adverse 

 situations and its scavenging habits might account in 

 part for its almost universal distribution throughout 

 the temperate zones. 



Cypridopsis smaragdina Yavra. (PI. XLVIII., Fig. 

 11-12.) 



1891. CypHdopsis smaragdina, Vdvra (68, p. 80, Fig. 261-263). 



Length .65 mm., height .45 mm., and breadth .34 mm. 



This striking and interesting form appears at first 

 glance, when seen from the side (Fig. 11), to be in the 

 shape of a half-moon, except that the under edge is 

 nearly straight. The shell is light to grass- green, es- 

 pecially on its dorsal aspect; alcoholic specimens, how- 

 ever, commonly show but a trace of this coloration. 

 Surface thickly covered with long hairs, which are all 

 parallel to one another, backwardly directed, and closely 

 appressed to the shell (Fig. 11). 



