Daphnia hyalina Leydig. 
Outline of female from Lake Minnetonka drawn to the same scale 
as figure 5. 
Head of a common form of the above species. 
Extreme development of the crest. 
Embryo illustrating the early development of the helmet. 
Daphnia kalbergensis Schoedler. 
Typical form, from Lake Minnetonka. 
A form of the above taken from the same gathering. 
Post-abdomen of the above. 
Extreme development of head resembling D. retrocurva Forbes, 
from same gathering as the above. 
Daphnia dentifera Forbes. Copy from ‘‘Aquat. Invert. 
Wyoming.” 
