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According to the second method of explanation the last-mentioned collection of bristles is to
be considered as a remains of the exopodite, the two distal joints presumably represent the
endopodite; the protopodite has the same extension as according to the former method of
explanation; cf. fig. VII: 2.
The collection of bristles that is in most cases to be found on the posterior edge of the
part that has been explained as a protopodite is thus, in my opinion, to be considered as the
rudiment of a homologon to the vibratory plate on the preceding limb. This assumption seems
to be supported both by the position of these bristles and by the fact that they are sometimes
Kig. VII. — Sixtli limb of Cypridina. mediterranea O. Costa (From G. W. Müller, 1894). 1. According to „the first
method of explanation“. 2. According to „the second method of explanation“ the first alternative.
attached to a lobe-like process, though the latter is small. It seems, at least at present, to be
impossible to prove this assumption. For the cause of a possible réduction of this vibratory
plate see U. W. Müller, 1894. p. 198.
There is no part that might be explained as an endopodite according to the first
method of explanation* (as in the fifth limb).
\Ye must note the uncertainty that, in my opinion, exists in both the methods of explanation
deseribed above, with regard to the boundary between the protopodite and the brauch situated
distally of this. Perhaps only the proximal joint, the one that in most cases is characterized by
lia-ving two bristle-bearing endites on the anterior edge, is to be considered as a protopodite. Or does
the exopodite (or the endopodite as the case may be) consist only of the large end joint? These are
questions that probably cannot be decided with certainty, at least at present. Of the three
alternatives mentioned above it seems to me, however, that the first, namely that the protopodite
comprises the two proximal joints, is the most probable and it lias been adopted in the present
work. This statement is supported, it seems to me, by a comparison between the fifth and
sixth limbs. It may be sufficient to refer to a comparison between the schematic figures,
reproduced above. of the fifth limb in the sub-family Cypridininae (figs. IV: 3, 4) and the figures,
II seems to me improbable that. il is represented by the joint ncxt to the onter one. Cf. the embryology of
the limb below.
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