326 



GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. 



Habitat: Cincinnati, Ohio. Very abundant in a shallow canal 

 basin in Camp Washington. Up to date it has not been found in any- 

 other locality. 



LATE LARYAL HISTORY OF CYPRIS HEKRICKI. 



Plates LXVIII, Figs. 40-42; LXIX, Figs. 3H-39. 



In this connection it is not intended to discuss the early stages of 

 Cypris HerricM. These remarks will be confined to what corresponds 

 to the seventh to ninth ecdyces of Cypria opthalmica Jurine. !Not only 

 that, but the remarks will be restricted to the external morphology. 

 It is hoped to discuss the internal anatomy in a subsequent paper. 



The earliest stage here discussed has been compared to the seventh 

 stage of Cypria ox>thalmiea Jurine, because in that stage the appendages 

 have attained about their permanent form; but it must not be sup- 

 posed that in this Cypris there are only two subsequent larval stages. 

 These stages are tabulated in the following table: 



In Cypria opthahnica (Jurine) Claus found that by the time the 

 seventh stage was reached, the shell had practically assumed its final 

 form. In the form here described there are pronounced differences 

 between the earliest stage here considered and the adult. 



In the adult of Cypris HerricM the dorsal border of the shell is 

 almost uniformly convex and the cephalic border of the shell is about 

 the same height as the caudal. In stage A (Fig. 33), however, the 

 shell is highest near the cephalic extremity, and the cephalic border 

 of the shell is higher than the caudal. As the animal passes through 

 stages B to D, the highest point of shell moves gradually towards the 

 middle and the height of the caudal margin of the shell approaches 

 more and more the height of the cephalic margin. 



