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 386


E ~ ~ ~  ~   ~  ~~icni X :dem
              386      Wtsconsin Academy of Sciences, Arts and Letters.
                The heart as seen from the side, shows a tube convex below
and con-
              cave above. It is truncated anteriorly, and the aorta issues
from its
              ventral side. From above the heart closely resembles that of
Latona,
              having the form of a broad sac, rounded behind, and widest
through the
              venous ostia.
                The shell-gland has a form in this genus, which is unique
among the
              Cladocera. It consists of three branches, of which the shortest
is dor-
              sal and extends toward the heart, the next in length is ventral,
while the
              longest extends posteriorly and may reach through two-thirds
of the
              length of the valve. This last loop is found only in Latonopsis.
The
              whole gland consists of a tube doubled on itself, whose course
can easily
              be traced. Beginning near the mandible in a bladder-like expansion
the
              tube passes into the valve and extends ventrally; it returns
on itself to
              the middle point, then passes backward in a long loop, returns
again to
              extend up toward the heart and come back to the middle. Then
comes
              a second posterior loop, lying parallel to and within the first,
and on its
              return the tube passes to its outlet near the mandible. Thus
there are
              two passages in the dorsal and ventral loops and four in the
posterior,
              not three as stated by Sars (op. cit. p. 9.). Sars' figure
(Pl. I, Fig 1.) shows
              the organ quite correctly.
                                      DESCRIPTION OF MALE.
                The male resembles in general the young female.
                The antennules are long and stout, being often nearly half
as long as the
              animal. They taper toward the apex, are curved, but not geriiculate.
They
              are provided with a long row of very fine teeth extending from
a point near
              the sense-hairs to the apex. They thus resemble in general
the antennule
              of the male Sida and Daphnella and differ widely from the male
Latona.
              Near the base of the antennule on the inner side is a stout
projection,
              rounded at the apex and covered with very fine hairs. This
projection
              is probably equivalent to the " appendix ciliata "
of the male Latona.*
              In Latona, Sars shows the appendix ciliata some way distal
from the
              olfactory hairs, while in Latonopsis, it is some way proximad
to these.
              My specimens of Latona, however, show the appendix close the
to sense-
              hairs; so that the difference of position does not interfere
with homol-
              ogy. The cilia on the appendix of Latonopsis are very fine
and easily
              overlooked; they are far less conspicuous than in Latona.
                The copulatory organs resemble those of Latona. They are
a pair of
              long, curved, flexible appendages, perforated by the vasa deferentia.
              They arise at the base of the post-abdomen and are long enough
to reach
              beyond the terminal claws.
                The first leg shows a very distinct and strong hook. In this
structure
              Latonopsis differs from the other Sididce and especially from
Latona.
                * Sars,JG. 0. Norges Ferskvandskrebsdyr. Cladocera Ctenopoda,
p. 55. P1. III, Figg. 17.
I'
In
I'
A


Go up to Top of Page