Page 379

       List of Crustacea (Jladocera from Madison, Wis.    379
LIST OF CRUSTACEA CLADOCERA. FROM MADISON,
                          WISCONSIN.
                          BY E. A. BIRGE,
               Professor of Zoology, University of, Wisconsin.
 In 1878 the writer published Notes on Cladocera in the fourth volume
of the Transactions of this Academy,* in which were noted twenty-five
speciebs of Cladocera found at Madison. Returning to the subject with
better means of collecting and a much larger command of the literature
of the group, I have been able to enlarge greatly the number of species
and to identify them more accurately. As the task of reviewing the
greatly scattered literature, especially of the Lynceidce, seems likely-to
occupy some time, it seems advisable to print a list of the species
already found, with notes on rare or new forms.
  A glance at the subjoined list of sixty-four species and varieties
regarded by many European writers as species, will show how close our
fauna is to that of Europe. Out of the whole number, only nine are
peculiar to this country and of these five are varieties of species found
elsewhere, or are very close to foreign species. Three species are deter-
mined as new, Latonopsis occidentalis from the Sididce, Moina sp. nov.
from the Daphnidce, Alona lepida from the Lynceidce.
  With the exception of five species and varieties (Daphnia pulex, D.
retrocurva, Alona tenuicaudis, and the species of Moina), all of the
species in the list have been found in Lake Wingra. This is a small lake
about one and three-fourths miles long and half as wide, with broad
margins of marsh all around it. In the marsh the water is from a few
inches to two feet deep between the areas of wild rice and reeds, and the
bottom is partly composed of vegetable debris and partly covered by a
dense growth of Chara. The lake itself hardly exceeds fifteen feet in
depth, and almost the entire bottom is overgrown with water plants
of various kinds. Among these weeds and in the marshes Cladocera
abound. The abundance of food and variety of locality offered proba-
bly account for the great number of species. In Lake Mendota, a
much larger body of water, six miles by four, and having a depth
of sixty to eighty feet, I have found only thirty-eight species of Clado-
* Vol. IV, 1876-7 (printed 1878), pp. 77-110. Pl. I, II.
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