3S8 
Wisconsin Academy of Sciences , Arts and Letters. 
BIOLOGICAL REMARKS. 
Latonopsis occidentalis was found in Lake Wingra, a small lake about 
one and three-fourths miles long with a broad margin of marsh. It 
lives chiefly in the marshy region although I have found it in deeper 
water — one to three meters. It is most abundant in openings among 
the reeds of the marsh, where there is a foot or so of water filled with 
algae and vegetable debris. In one such spot it was especially abundant 
during the summer of 1891. A single haul of the dredge would give 
from six to thirty individuals. I have dredged it with Latona in the 
open water, while I have never found Latona in the marsh. Sars’ speci¬ 
mens came from a clayey mud. I have never found this species in 
muddy water. 
In the aquarium it behaves quite like Latona. It often remains sus¬ 
pended and motionless in the water, and can often be turned over with 
the dropping tube without disturbing it. When, however, it decides to 
move it starts very suddenly. Its movements are less vigorous than 
those of Latona , as would be inferred from the different structure of 
the antennae. 
I have never seen more than eight young in the brood cavity. There 
are two sexual eggs, for whose reception a special cavity is enclosed, 
although there is no true ephippium. 
The males appear in the latter part of July and the first part of 
August, and in September no specimens of either sex could be found, 
while Latona was more plentiful at this time than earlier in the season. 
Constant observation at any small lake will convince the student that 
the appearance of the males does not depend on temperature or any 
other simple cause. Each species has its own time for sexual reproduc¬ 
tion, which is related to external influences in the same complex way 
as is the flowering of plants. 
Species 8. Moina, spec. nov. 
A species of Moina , apparently new, has been found, but it is not as 
yet thoroughly worked up and will probably form the subject of a spec¬ 
ial paper. It seems related to M. bracliiata , Jur. and was at first identi¬ 
fied with this species. Further study, however, showed that there was 
only one egg in the ephippium and that the structure in other particu¬ 
lars differ from M. bracliiata. The male especially shows peculiarities 
not found in other species. 
Species 21. Daphnia hyalina, Leydig. Plate- XIII. Fig. 9. 
Into this species have been united D. galeata , Sars, D. pellucida, P. 
E. Muller and D. gracilis , Hellich. Two well marked varieties are found 
at Madison. One with pointed crest is found in Lake Wingra, and the 
other whose crest is rounded is found in the larger lakes. Although the 
