172 GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. 
men 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. 
Ceriodaphnia quadrangula Mueller. 
PLATE XLI, Fias. 16-18. 
Daphnia quadrangula—O. F. Mueller. 
Daphnia reticulata—Baird. 
Head depressed, rounded at the end, only slightly angled; fornices 
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. 
*Ceriodaphnia scitula Herrick. 
PLATES XLII, Fias. 5-8; XLIV, Fias. 1, 2; XLV, Fia. 1. 
One of the most abundant species of Ceriodaphnia in Minnesota is a 
large form much resembling C. quadrangula. The post-abdomen is 
exactly as in ©. 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 hexagonal 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 extending down the en- 
tire inner side. The size is 0.8 to 1.0 mm.; color pinkish, opaque; 
antenne, especially, often bright pink. Male 0.6 mm.; flagellum of 
the male antenne long; sensory filaments lateral, also one anterior, 
lateral flagellum. 
Distinguished from C. quadrangula by the prominent fornices, large 
anal spines, small reticulations, form of head and larger size. 
A small variety resembling the above very closely is the common- 
est form in our larger lakes; the reticulation is commonly larger but 
less distinct, the head is depressed and narrowed, with a sinuous 
upper outline. The fornices are prominent and the form of the post- 
abdomen is exactly as in the last. The spines of the post-abdomen 
are very long and seated on small eminences. The length hardly ex- 
ceeds 0.55 mm. The claw is densely ciliated, but not spined; these 
bas 
