University of Wisconsin Digital Collections
Link to University of Wisconsin Digital Collections
Link to University of Wisconsin Digital Collections
The State of Wisconsin Collection

Page View

Transactions of the Wisconsin Academy of Sciences, Arts and Letters
volume VIII (1888-1891)

Birge, Edward A.
List of crustacea Cladocera from Madison, Wisconsin ,   pp. 379-Plate XIII ff. PDF (7.9 MB)


Page 389


                   Lest of Crustacea Cladocera from Madison, Wis.     389
           -lakes are only a mile apart, I have not found the pointed variety
in
           Mendota or the rounded in Wingra. The outlines of the head are
very
           -variable, the variations quite closely resembling those represented
in
           -D. berolinensis, apicata, and eucullata, although of course this
species has
I i       the macula nigra.
             The males appear in the latter part of September. The flagellum
of
           the antennule is convex stout and short, usually little longer
than the
           sense-hairs. The anterior sense-bristle in our specimens lies
little nearer
           -the end of the basal portion of the antennule than the head.
In this our
           specimens differ from Eylmann's * description, who says of it,
that it is
           "von der Endborste nicht weit entfernt."'
             This species is the most abundant in the open waters of the
Madison
           lakes. I have also obtained it from Minnesota and Michigan, showing
           some variation from our form in each case.
           Species 24. D. KAHLBERGENSIS var. RETROCURVA, Forbes. Plate XIII.
               Figs. 7, 8.
             This form was first described by Forbes * as a distinct species.
It is the
           Most extreme Daphnid form yet observed. I cannot agree in the
state-
           ment of Forlbbsthat the large helmeted forms predominate in the
smal-
           ler lakes (I. c. p. 643.) At Madison the forms of D. hyalina and
of D.
           retrocurva in Lake Mendota are much more helmeted than those in
Lake
           Wingra. The former lake is about six miles by four, the latter
           1-4 by 34 mile. D. hyalina in the smaller lake is more like D.
apicata,
           while in Mendota the crest is more developed than is shown by
any
           iEuropean descriptions. D. kahlbergensis from Wingra shows the
forms
           typical of that species and of cederstroemii while the full development
           o f  t__ e - c r e s t - o n l y - c o m c s - i u   t h e   u
r   l kE .   T - m e M s _ss  Us  i e - p
           pear late in the fall, in the latter part of October and in November.
           The head is of the kahlbergensis type, sometimes curved up but
never
           showing the extreme development of the female. The antennule has
a
           flagellum a good deal longer than the sense-hairs, curved at the
tip and
           distinctly articulated to the basal part.
             Our specimens do not show the extreme development of the head
be-
           fore birth noted by Forbes (1. c., p. 642). The head in the young
is not as
           much crested as in the adult D. hyalina. This species is always
found
           -in company with D. hyalina and is far less numerous. On calm
summer
           -nights the water of Lake Mendota swarms with these two species,
to-
           gether with a Cyclops, a Diaptomus, and Leptodora hyalina. They
are
           not abundant close to shore and seem to spend the day in swarms
at the
* Eylmann, E. Beitrag zur Systematik der Europiischen Daplniden, Freiburg
i. B. 1886,
p. 33.
* Forbes, S. A. Entomostraca of Lake Michigan and adjacent waters. American
Natur-
alist. Vol. xvi., p. 642, August, 1882.
M-W ;
-  L. I ;,
l
I
i
I
I I
4
11
I
a
L


Go up to Top of Page