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Why does not the proximal, joint-like process represent the first joint of a two-jointed
protopodite? Or — if it vvere to appear that a similar process exists in the genus Cytlierella
as well, which does not seem improbable, first because of a drawing of this antenna given by
G. W. Müller, 1894, pl. 32, fig. 1, and secondly because of what I have observed myself in
a préparation of a similar antenna* — why s h o u 1 d w e not assume a t h r e
e-j o i n t e d p r o t o p o d i t e? This number is as a matter of fact assumed by H. J. Hansen
as the original one for all the post-oral limbs of the Cruslacea (cf. Z o o 1. A n z. 1893, p. 194).
In a new form (not described)**, closely related to the genus Macrocypris 1 observed that this
basal part is composée! of two clearly separated segments. Why then might it not be assumed
that this process is homologous with the procoxale and the coxale, so that the large joint that
foliows is homologous with the basale? The formation of a knee would thus in these forms
too have taken place between the basale on the one hand and the exopodite and endopodite on the
other. As in the case of the mandible of the Cypridinids a ventrally pointing knee would
have been developed between the coxale and the basale. Before it has been clearly proved that
these homologizations are impossible we cannot accept the view put forward by G. W. MÜLLER.
G. W. MÜller’s assumption with regard to the endopodite of this antenna of the
Protostracods seems to me almost equally unfounded. This would resemble most
closely this brandi in the Polycopids.
The endopodite would have been four-jointed. According to G. W. MÜller’s
Statements the recent Ostracods have the following number of joints on this branch.
Leav-ing out of considération forms with a more or less reduced endopodite, the Cypridinids
have three joints. Among the Halocyprids the female (the male is unknown) of
Thaumatocyyris, which is in several respeots presumably the most primitive genus,
has only two joints; in the other forms of this group we always find in the males more
or less distinetly three joints, in the females most frequently only two joints. The P o 1
v-c o p i d s, the group that would possess the most primitive second antenna, appear always
to have three joints. The C y p r i d s sometimes have a four-jointed, and sometimes a
three-jointed, endopodite; in the cases where a three-jointed endopodite is found the end joint has
either more or less entirely disappeared or else the second joint has arisen by a union of two
joints; traces of this union can still be observed in some forms. Darwinulidae has three joints;
the second joint would have arisen by the union of two joints, but there seems to be no traces
of this union present; no such traces are at any rate to be seen on figures hitherto published,
nor are they mentioned either by G. W. MÜLLER or other writers. Nesideidae is characterized
by four joints. The Cyt herids have three or four joints — in the cases in which three
joints are found the second joint would have arisen by a union of two joints; traces of this union
can sometimes by observed. The Cytherellidae have three joints; the second of these would
show „deutliche“ traces of a union (1894, p. 43); no such traces can. however, be found on the
figure given by G. W. Müller (1894, pi. 32, fig. 4), nor have I succeeded in observing any on a
specimen investigated by me.
* The préparation was unfortunately defective.
** To be published in a following part of this work.
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