200 GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. 



from the body by a marked depression. The spine of the shell springs 

 from the upper angle or is quite wanting. The post abdomen is of 

 moderate size, somewhat narrowed toward the end. The claws are 

 smooth, the anal spines nearly equal, straight, about fourteen in 

 number. The abdominal processes are not coalesced or but slightly 

 so. Length 1.50 mm. to 2.0 mm. The species was collected sparingly 

 in a large gathering of D. pnJex from a small lake in early spring. 



"The size and conformation of the abdominal processes are very 

 variable and the long and very slender spine is frequently absent." 



The antennules are very short. Males unknown. 



Daphnia microcepliala Sars. 



A small transparent form, head, only half as deep as the shell, 

 slightly concave ventrally and ending in a short blunt beak. Shell 

 elongate oval with a slender somewhat curved spine from the middle 

 of the caudal margin. Abdominal processes nearly equal and united 

 at the base. Anal spines seven. Claws without teeth. Length 0.75 mm- 



This is also a species requiring farther study. 



Daphiiia cavifrons Sars. 



A reddish species with the head separated from the body by a 

 depression, depressed, ventral border excavated, beak large. Shell 

 ventricose with a short spine from near the upper angle. Abdominal 

 processes nearly equal and united at the base. Anal teeth 12. Claw 

 without teeth. Length 1.5 mm. 



I am not sure of this and the preceding. 



* Daphnia rosea Sars. 



Of moderate size, reddish in color, and resembling D. longispina. 

 Head depressed and not separated by a dej)ression from the thorax, 

 somewhat excavated in the ventral margin, beak blunt. Shell oval, 

 spine long, springing from above the middle and directed obliquely 

 dorsad. The two abdominal processes thick, equal, discrete. Anal 

 spines 12 to 14. Claw without teeth. Length 1.9 mm. 



The American form identified with this species is more like D. 

 longispina. 



Daphnia aquilina Sars. 



A species of medium size, transparent. Head depressed, protuber- 

 ant at the eye, excavated behind it, the beak lying in the same plane 

 as the frontal projection and strongly curved caudad. Eye large. 

 Shell oval, slightly separate from the head. Spine above the middle 



