NOTES ON CLADOCERA. IV. 
EDWARD A. BIRGE. 
I have recently sent to the press a brief synopsis of the 
known Cladocera of the United States, for a forthcoming work 
on fresh-water biology by Professor H. B. Ward. In the 
course of preparing this synopsis it was necessary to settle, 
provisionally at least, several questions of nomenclature, one of 
which is more fully discussed here. It seemed also advisable 
to include in the synopsis several species hitherto undescribed. 
I publish, therefore, the following notes in order that the mat¬ 
ters in question may appear in a scientific journal and in 
more complete form than is possible under the conditions of 
extreme brevity imposed by the limits of a general work. 
Type specimens of all new species described are preserved 
in the collections of the Wisconsin Geological and Natural 
History Survey at Madison. 
1. Pseudo sida bident at a Herrick. 
Plate LXVII, figs. 1-9; Plate LXVIII, fig. 1. 
In 1903 I visited the southern part of the United States, 
collecting entomostraca; being especially desirous to clear up 
the confusion which exists with regard to the genus Pseudosida 
Note. —The former papers of this series have been published as fol¬ 
lows: 
Notes on Cladocera. Trans. Wis. Acad., Vol. 4, pp. 77-110, pi. I, 
II. Madison, 1878. 
List of Crustacea Cladocera from Madison, Wisconsin. Trans. 
Wis. Acad., Vol. 8, pp. 379-398, pi. XIII. Madison, 1891. 
Notes on Cladocera. III. Trans. Wis. Acad., Vol. 9, pp. 275-318, 
pi. X-XIII. Madison, 1893. 
My stock of separates of these papers has been distributed. 
