40 TWELFTH ANNUAL REPORT. 



prominent. The shell is large-reticulate and the abdomen is large 

 and obliquely truncate, the anal teeth being very large and strongly 

 curved. The only individuals wseen were ephippial females measur- 

 ing .55 mm. This maj' be. 



Sp. lO. Ceriodaphnia censors, Birge. 



This species differs from C. laticaudata in one or two points, 

 being about one-half the size and having fewer caudal teeth. Birge 

 says the abdomen is broad and obliquely truncate. The difference 

 between being obliquely truncate and narrowed at the end in some 

 circumstances disappears, so that really this species seems quite 

 close to laticaudata. 



Found in Madison, Wis. 



Sp. 11. Ceriodaphnia quadraugula, Mueller. 

 (Plate A. Figs, 17-18,) 



Daphnia quadrangula, O. F. MUELLEB. 



Daphnia reticulata. BaIRD. 



Ceriodaphnia quadrangida, P. E. MUELI ER. 



Head depressed, rounded at the end, only slightly angled; forni- 

 ces prominent, antennules large; post-abdomen narrow, of equal 

 width for the lower half, rounded at the end, with about eight 

 small spines; claws smooth, length about 0.6 mm. This species 

 resembles a smooth-clawed D. reticulata. 



Sp. J 2. Ceriodaphnia scitula, (Sp. n.) 



(Plate B. Figs. 5-7.) 



One of the most abundant species of Ceriodaphnia in Minnesota 

 is a large form much resembling C. quadrangula. The post-ab- 

 domen is exactly as in C. reticulata or C. dentata, which latter it 

 resembles in having a sharp angulation in front of the antennules. 

 The shell is oblong and heavily marked with minute, regular hex- 

 agonal lining; the upper angle is rather sharp. The head is closely 

 appressed, the fornices are prominent and abruptly truncate at the 

 tip, the eye is small, the pigment fleck also small; antennules short. 

 The post-abdomen is of moderate size, narrowed toward the end 

 and armed with about ten powerful curved spines; the terminal 

 claw itself is large and curved, armed only with fine spines extend- 

 ing down the entire inner side. The size is 0.8 — 1.0 ram.; color 

 pinkish, opaque; antennae, especially, often bright pink. Male 0.6 



