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M audible.
lias fewer joints than the endopodite. With regard to tlie nuinber of joints in the endopodite
of the second antenna in different Ostracod groups I need only refer to what is written about
this limb in the second chapter of this work. The weight of the evidence afforded by the position
of the end joint of the inner branch is well illustrated by the faet that in the H a 1 o c y p r i d s
as well as in the Polycopids the end joint has a dorsal position, when the branch
is pointing forwards contrary to the statement of G. W. MÜLLER (see my fig. 12 of
Halocypris brevir ostris). A close comparison between Halocyprids, Polycopids,
Cyprids, Darwinulids, Nesideids and Cytherids will also afford good
material as to the strength of the evidence of the number of the end bristles; it must be
described as nil. There is no additional resemblance between the homologized branches, at least
according to G. W. MÜLLER — and my own expérience does not contradict this idea. The
muscular system, for instance, shows, as anyone can easily ascertain, far-reaching differences
in this limb in the different Ostracod groups. G. W. Müller stated that he was surprised
„durch den Mangel jedweder deutlichen morphologischen Beziehung zwischen den einzelnen
Gliedern; mindestens fehlte jeder Anhalt dafür, wie eine Form aus der anderen, oder beide aus
einer gemeinsamen Stammform abzuleiten seien“ when using the old homologization. He
might have experienced the same surprise on comparing the exopodite in, for instance, the
C y p r i d i n i d s and the Cytherellids. These are both essentially different from
each other — but nevertheless it is certain that they must be homologous.
The faet that it is not possible to observe any far-reaching morphological agreement
between the homologized branches of the Cypridinids, Halocyprids and
Polycopids on the one hand and the other Ostracod groups on the other does not, however,
render the homologization carried out by G. W. Müller in any way less probable, as the.
morphological differences between the former groups and the latter are so far-reaching in other
respects as well that no close agreement between these limbs can be expected a priori.
Mandible: — This limb appears as a very uniform type in the different Ostracod
groups. It has not been a subject for any important differences of opinion among preceding
authors: we may note, however, that several of these authors have not given any opinion as
to the morphological value of its different parts; thus the small appendage on the Cypridinid
mandible, which is interpreted as the exopodite in this work, is often called simply „appendage“.
Apart from one important exception I have followed in this work the homologization
used by G. W. Müller in his work of 1894.
According to this writer the mandible, like the second antenna, is almost always
deve-loped as a biramous limb. The protopodite is powerful, and in most cases it is distinctly divided
into two well developed joints, the coxale and the basale; in some Polycopids even three
distinct protopodite joints are to be distinguished on this limb, see my fig. 5 of Polycope setigera;
sometimes the protopodite is fitted with two powerful endites, one on the coxale and one on the basale
(Halocypri d s) ; in most cases, however, it has only one endite, which is situated on the coxale.
1 lie latter endite in, for instance, the Polycopids and Cyprids and most of the
C y t h e r i d s is very powerful, but in the Cypridinids, on the other hand, it is weak
and in most cases small and is not used as a masticatory organ; in a number of forms belonging
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