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Hnd-shaped organ.
Summary of my
criticism nf G. II .
Midler’s opinion of
ihr Protostracods.
The fundamental
classification of the
recent Ostracods
accord mg to G. II .
Midler.
the P r o t o str a c o d s consistée! of two simple sacks situated in the posterior part of the
body; from each of these sacks there was a simply constructed duet, opening out ventrally
just in front of the furca; on the other hånd it seems to me to be quite uncertain
whether the sexual duets opened outwards with a simple or a paired orifice. In the males
the posterior pair of legs was used in copulation and was developed into the two penes.
The fate of this pair of legs in the females is uncertain; there is possibly a remains
of them in the genital verrucae. Among the recent Ostracods the most primitive
conditions seem to be found in a number of Cypridinids, possibly, for instance, in
Philo-medes and Asterope.
Did the Pro t ostracods have a rod-shaped organ?
G. W. MULLER does not make any statement on this point either. C. CLAUS expresses
himself (1876, p. 97) in such a way that one can scarcely doubt that he considered that they
had. I scarcely think, however, that they ha d. Among the recent
Ostracods this organ is absent not only in C y p r i d s, Darwinulids, Nesideids,
Cytherids, but also in Cytherellids and P o 1 y c o p i d s, which we are accustomed
to consider as being in many respects rather primitive and in the genus that is in several
respects presumably the most primitive among the Halocyprids, narnely T haumatocypris.
Only in the Cypridinids and most of the Halocyprids is it developed. I myself
have only had an opportunity of investigating one species of Polycopidae. This was
charac-terized by two bristles, situated rather near each other on the front of the head, on
each side of the place where the rod- shaped organ is situated in the Cypridinids. Do
these bristles correspond to the similarly situated bristles in other lower Crustacean groups?
Is this a primitive stage? It seems to me by no means impossible that this is the case. It seems
difficult to assume that a rod-shaped organ existed originally and was then completely reduced
in all these forms. The faet that this organ is absent in the most primitive genus of the
Halocyprids even seems to indicate that the appearance of this organ in Cypridinids
and Halocyprids is not, as C. CLAUS has assumed, the result of common inheritance, but
that we have liere once more a phenomenon due to convergence.
This investigation has thus shown that while it is true that we can say with some
degree of certainty in the case of a number of characters that they are original, our whole
knowledge of the organization of the Protostracods is very incomplete and uncertain, a
good deal more uncertain than one would imagine from G. W. MÜLLER’s exposition.
G. W. MÜLLER gives the results of his investigation of the mutual relationships of
the recent Ostracods in his monograph of 1894. pp. 188—191.
The most important of these results is that the recent Ostracods are to be divided into
two main natural groups, sharply divided from each other, Myodocopa and Podocopa. To the
former belong C y p r i d i n i d s, Halocyprids and P o 1 y c o p i d s, to the latter
C y p r i d s, Darwinulids, Nesideids, Cytherids and Cytherellids.
The view that these animais can be divided into two natural, sharply differentiated
- „scharf getrennte“ — main divisions is, as is shown above, decidedly opposed to the views
of G, O. Sars and C. Claus. As a matter of faet G. W. Müller is almost alone in this view.
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