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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 383

6
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                List of Crustacea Cladocerca from Madison, Wis.       383
        ber at various localities near Madison. It lives in clear water among
        mweeds,l d va dredge which can be dragged through the weeds and not
        wd merely above them is needed in order to secure it. With the cone-
        dredge it is not difficult to obtain 20 to 100 specimens. The same
may
        be said of such bottom forms as Ophryoxus and Drepanothrix.
          Sars speaks feelingly of the difficulties which beset one who attempts
        to view this powerful and obstinate cladoceran from the side. If
a life-
        box is used and a trace of 2 per cent. of solution of osmic acid
in water
        is added to the water containing the animal, there will be little
trouble
        in turning it on its side. After the poison begins to act, it is
best to at-
        tempt turning the animal by rotating the cover of the life-box. If
left
        to die undisturbed the antennae are usually expanded while an irrita-
        tion applied to it while alive causes it to fold the antenna3 along
its
        sides, when it can readily be turned into any position.
        Species 6. LATONOPSIS OCCIDENTALIS, sp. nov. Plate XIII. Figs. 1-5.
          In 1888 G. 0. Sars* established the genus and species Latonopsis
        australis for a new form of the Sididcp raised by him from mud obtained
        from Australia. I have found here a second and closely allied species
of
        this new and remarkable genus, and have succeeded in finding males
        which did not developein Sars' aquaria.
          Latonopsis, Sars, is closely ailed to Latona, Sars, and may be
charac-
        terized as follows:
                                   :LATONOPSIS, Sars.
        r Impression between head and thorax slight or wanting. Labrum
        devoid of plate-like expansion. Antennule with a long, plumose, straight
        or curved flagellum, articulated to the basal pat Antenna with simple
        rami, the superior ramus bi-articulate, the inferior tri-articulate,
as in
        Daphnella. Heart concave dorsally, truncate anteriorly, the aorta
arising
        on the ventral side. Shell-gland with three long branches. Male (of
        L oceidentalis, Birge, at least) with simple copulatory organ, and
hook
        on first leg. Antennule long, slightly curved, armed with fine teeth
re-
        sembling in general the antennale of Sida, but having a median projec-
        tion near the base. Color of both species yellowish-transparent.
                                       SPECIES.,
           a. Fornices absent.  Antennule shorter than anterior margin of
                head.                                        L. australis,
Sars.
           b. Fornices present. Antennule longer than anterior margin of
                head.                                   L. occidentalis,
sp. nov.
          * Sars, G. O.rAdditional notes on Australian Cladocera raised from
Dried Mud. Chris
          tiania 1888, pp. 6-15. PI. L Christiania Videnskabs Selskabs Forhandlinger
1888. No. 7.
I ,


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