12 



BULLETIN OF THE LABORATORIES 



TABLE I. 



In Cypi'ia opthalmica (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 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. 



In the adult Cypris Herricki, the caudal margin of the shell is 

 entire. But in stage A, the caudal margin of the shell is bordered 

 with minute teeth [fig. 34], In this stage the teeth are quite small 

 and might easily be overlooked; but in stage B [fig. 35], these teeth 

 have become very conspicuous. Indeed, they are the characteristic 

 feature of the shell. These teeth are present throughout stage A to 

 D, but in stage D they have begun to disappear. In the adult stage 

 there is no trace of these teeth. 



