« . 
, 
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 LARVAL HISTORY OF CYPRIS HERRICKI. 
PLATES LXVIII, Fies. 40-42; LXIX, Fias. 33-39. 
In this connection it is not intended to discuss the early stages of 
Cypris 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. 
The earliest stage here discussed has been compared to the seventh 
stage of Cypria opthalmica 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: 
Stages.| Length. Height. Position of Dorsal Hump, Ete. Form of Post-abdomen. 
—| 
| Rudimentary; fewer spines. 
A 0.90mm. | 0.57mm. /| Some distance in front of middle. vale aa fica Gananee 
Teeth on caudal margin of shell. than remainder of the ap- 
pendage. 
4 - z 4 : | Form normal; number of 
% 1 Sa Oy mm Approaching middle. spines normal : ratio of 1he 
1.38 mm | 0.84 mm Teeth on shell much larger. weten nH aie ae 
P | Ratio of the length of ter- 
| 1.98 mm 1.20mm, | Near the middle. | minal spine to the lergth of 
Cc Teeth hell] post-abdomen more uearly 
| eeth on shell large. normal than in B. 
| 2.79 mm 1.64 mm At middle. About as in adult. 
Dat Teeth disappearing. ‘ 
Adult. | 3.00 mm. At middle. 
No teeth on shell. 
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. 
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