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vibratory plate may certainly seem, at first sight, to support the assumption that we are also
concernée! with an epipodial appendage in the case of the maxilla in these groupa. This argument
will, however, count very little with those who take the saine view with regard to the
morpho-logical value of the different parts of the limbs in Protostraca as that given above on p. 24.
The situation and function of the vibratory plate support the assumption that we are concemed
with an epipodial appendage; in the Cypridinids, in addition, there is often, as we have seen
above, an appendage which is situated at about the corresponding place on the maxilla and
whose epipodial nature seems to be quite certain.
In short it seems to me at present quite impossible to find any more decisive proofs
for the real morphological value of the different parts of the maxilla in the C y p r i d s,
Darwinulids, Nesideids and Cytherids. Under these circumstances would it
not be best to accept the terminology used by the majority of the later writers on this subject?
This would perhaps have been most correct. I have, however, allowed my personal opinion to
prevail in this matter. The homologization adopted by me differs in one important point
from that of previous authors: I take the vibratory plate on this limb too as an epi-
podial appendage. In accordance with the view taken by previous writers I look upon the
distal part of this limb as an endopodite. It seems to be rather probable that this explanation
is correct. At any rate the possibility that it is right must be considered as an open question.
In the case of the maxilla of the Cytherellidae too the difficulty of carrying out a certain
homologization of the different parts is very great. The proximal part with its three endites
may very well correspond to the two proximal joints of the protopodite, the procoxale and
the coxale. There is the same uncertainty with regard to the palp and the vibratory plate as
there is in the case of these organs in the Cyprids, Darwinulids, Nesideids
and Cytherids. It seemed to me most convenient to adopt the homologization
accepted above for these four groups in the case of the first-mentioned group as well.
The explanation of the two appendages situated distally on the basale of the maxilla
in the family Cypridinidae as an exopodite and an endopodite has already been made by
C. CLAUS, 1865. This author writes concerning the exopodite (loc. cit. p. 151): „Jedoch geschieht
hier“ (W. Liljeborg, 1853) „des schmalen Anhanges keine Erwähnung, welcher bei unserer
Art an der Spitze drei Borsten trägt und dem am ersten Maxillenpaare von Cypris und Cythere
mächtig entwickelten ,Kiemenanhang1 zu entsprechen scheint.“ The vibratory plate,
„Kiemenanhang“ on the maxilla of Cypris and Cythere is explained by this writer as an exopodite.
C. CLAUS based this homologization especially on the important fact that in young larvae „noch
im Brutraume des Mutterthieres“ these two appendages are developed more similarlv (cf.
C. Claus, 1865, p. 150, pi. X, fig. 6) and that it is only later on that the endopodite grows stronger
in proportion to the „appendage“. A similar opinion is expressed by G. O. SARS, 1887; he
identifies this process with the „saakaldte Branchialplade“* in the C y p r i d s and C y t h
e-rids; he does not, however, give any reasons in support of this view. On the other hånd
G. W. MÜLLER, in his work of 1890, has an explanation of this limb in the family Cypridinidae
which differs exceedingly from that adopted in the present work. This writer describes the
* This writer expressed no opinion as to the morphological interpretation of this „Branchialplade“ (branchial plate).
Cytherellidae.
H istorical.
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