‘ ; Pik ri ay ee 
326 GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. | 
Habitat: Cincinnati, Ohio. Very abundant in a shallow canal q 
basin in Camp Washington. Up to date it has not been found in any 
other locality. re : 
LATE LARVAL HISTORY OF CYPRIS HERRICKI. 
PLATES LXVIII, Fias. 40-42; LXIX, Fies. 33-39. 
In this connection it is not intended to discuss the early stagesof 
Oypris Herricki. 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. % See 
The earliest stage here discussed has been compared to the seventh 
stage of Cypria opthalmica Jurine, because in thatstagetheappendages 
have attained about their permanent form; but it must not be sup- 
minal spine to the le gth of 
posed that in this Cypris there are only two subsequent larval ie ie beh. 
These stages are tabulated in the following table: y e. 
P $ St 
tle 
Stages.| Length. Height. Position of Dorsal Hump, Ete. Form of Post-abdomen. 1 
Rudimentary; fewer spines- Bp. os 
A 0.90mm. | 0.57mm. | Some distance in front of middle. fea a jouer se ieee 7, ie 
Teeth on caudal margin of shell. than remainder of the ap- a 
‘| pendage. . fr 4 
4 * i 
i 1.32mm. | 0.71mm. | Approaching middle. ace xa elec: beer bt = Cy ee 
to to length of the post-abdomen. 
1.38mm. | 0.84mm. | Teeth on shell much larger. greater than in adult. % 
1,98 mm. | 1.20mm. | Near the middle. Ratio of the Jengtt as ; 
Teeth on shell large. shige ete © nearly Pag 
~  |2,79mm. |1.é4mm, |Atmiddle. | © | Aboutasinadult, 1” oy 
v4 Teeth disappearing. ey. 2 
Adult. | 3.00 mm. Atmiddla.  e™ See ee ee hy an ks aE 8 Ba 
No teeth on shell. ¢ Pa Sea 
In Cypria opthalmica (Jurine) Claus found that by the time the 
seventh stage was reached, the shell had practically assumed its final — 
form. Inthe form here described there are pronounced differences. 
between the earliest stage here considered and the adult. 
In the adult of Cypris Herricki 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. 
