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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 396

Nt                 A          N            -     P                  M
396      Wisconsin Academy of Sciences, Arts and Letters.
in general, and include both names. In no case have I found the head
directed so horizontally forward as in Schoedler's figures of C. rectiro-
stris.* Nor are the posteal teeth so large. Our form more nearly resem-
bles that figured by Matiie.t In the other form, the head is more depres-
sed, the macula nigra larger than the eye, and the ventral margin of the
valves is concave. I have found no specimens connecting the two forms
and have therefore identified them as above.
  In both species I have found individuals in which the beak was trun-
cate, resembling that part in C. Lilljeborgii, Schdl., as figured by Hellich,4
or C. latirostris, Kurz.ß The shell markings differ from those figured
by
any author. If a cast shell is examined without cover glass and not
covered by water, a reticulated area is seen in the anterior part of the
valves just below the middle. From this radiate most of the stria.
These are in front parallel to the anterior edge of the shell and the
direction gradually changes until they are parallel to the ventral edge.
Sixteen or more stria run out on the ventral edge of the shell. The long-
itudinal strike anastomose occasionally and those on the dorsal part of
the valves do not bend downward into the reticulated area. I have never
found specimens reticulated all over with quadrangular meshes as Hel-
lich (l. c., pp. 76-77) figures them.
Species 63. POLYPHEMUS PEDICULUS, De Geer.
  This species I have found very rarely. Only two or three specimens
have been discovered at long intervals. Zachariasil notes that this ani-
mal is distinctly northern in its range. My observations confirm his
conclusion. I find it quite abundant in a small collection from northern
Minnesota. Herrick also describes it as plentiful in Minnesota. As I
have often searched vainly for it here, I believe that this locality must
be close to the southern limit of its range. The same is probably true of
Bfolopedium gibbersm, Zad.
Species 64. LEPTODORA HYALINA, Lillj.
  I quote this species by its old name, without passing on the correct-
ness of the change to L. Kindtii, Focke. Focke's paper is inaccessible to
me. Leptodora is very abundant in all our lakes. It grows to a large
size and specimens 18-21 mm. in length are not rare.
  * Schoedler. J. E. Neue Beitrige zur Naturgeschichte der Cladoceren, 1853.
PL. III, fig 50.
  t Matile, P. Die Cladoceren der Umgegend von Moskau. 1890. P1. IV, fig.26.
  t Hellich, B. Die Cladoceren Boehmens, 1877, p. 77, fig. 37.
  ß Kurz, W. Dodekas neuer Cladoceren, 1874, PI. II, fig. 9.
  I Zacharias, 0. Die Fauna des grossen und kleinen Teiches in Riesengebirge,
Zeit. Wiss.
  Zool. Vol. XLL, p. 492.
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