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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 382


382      Wisconsin Academy of Sctences, Arts and Letters.
                   NOTES ON THE PRECEDING LIST.
Species 1. HOLOPEDIUM GIBBERUM, Zad.
I have found this species only once in Madison. It is quite abundant
in collections from northern Minnesota, and Forbes* notes its occurence
at Grand Traverse Bay, Lake Michigan.
Species 2. SIDA CRYSTALLINA, 0. F. Mtfller.
No specimens were found belonging to the form S. elongata, DeGeer.
Species 3 and 4. DAPHNELLA BRACHYURA, Li6v. and D. BRANDTIANA Fisch.
Of those closely allied forms I have only to say that both are found
with us, and show exactly the same differences as described and figured
by Sars in his Norges Ferskvandskrebsdyr. D. brachyura is usually found in
open water, and D. brandtiana in marshes. I cannot state this as a law,
however, as both forms are found together sometimes, in either kind of
locality.
Species 5. LATONA SETIFERA, 0. F. Miller. Plate XIII. Fig. 6.
  Our specimens of Latona have one peculiarity not mentioned by any
European writer. There is a thick coat of short hairs on the head, body
and antennae. These hairs are .02 mm. or less in length, are close set and
give the outline a velvety appearance when seen by transmitted light.
P. E. MUller t says: " Hvad der er aldeles eiendommeligt for Latona
og
neppe jagttaget hos nogen anden Cladoceer, eret fint Lod af ganske korte
Haar, der isaer findes over Matrix; det er vanskeligt at see og opdages
kun ved staerkt Sidelys." This exact account shows that his specimens
were not villous as ours are. The hairs are conspicuous in any light and
are very easily seen. No other European writer mentions a similar struc-
ture. A more extended study of specimens from different localities will
show whether this is a local peculiarity or is characteristic of a distinct
variety. On old females which have not moulted recently the hairs are
worn off.
  The male antenna differs somewhat from the account given by Sars.$
  The appendix ctliata is much larger than Sars figures it, and is situ-
ated at the same level as the sense-hairs instead of distal to them.
The size, number and arrangement of the seta3 on the edge of the cara-
pace differ from the details given by Sars, but not in any very important
respect.
  Latona seems to be rare in Europe, but the apparent rarity is, as Sars
says, probably due to its mode of life and the method of collecting. In
late summer and early fall, one can be certain of obtaining a good num-
0 Forbes, S. A. On some Entomostraca of Lake Michigan and adjacent Waters.
Am.
Naturalist, vol. xvi., p. 641. Aug., 1882.
t Muller, P. E. Danmarks Cladocera, pp. 97-98.
$ Norges Ferskvandskrebsdyr, p. 55, Pl. III, figs. 17a, 17b.


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