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Furca.
Frontal organ.
Other organs.
The larval stages.
whether the.se folds are arranged segmentally or not). Fr. MÜLLER, 1870, p. 273, had already
expressed this view; as did C. CLAUS also, 1876, p. 96. As a proof of the probability of this
assumption it may be pointed out that weak transverse folds have been observed on the
dorsal side of the back of the body in the males of a number of species belonging to other genera
of C y pr id i nids; ci, for instance, Cypridina dorsoserrata G. W. Müller, 1908, pl. IV,
tig. 2. In the male of Cypridina Hilgendorfi G. W. Müller, 1890, we find at the corresponding
place gilis in the form of comparatively high transverse folds, seven in number; as in the
last-mentioned species but contrary to the genus Asterope, these folds extend across the back
without any median break; only the foremost one has a medial concavity. G. W. MÜLLER,
1890, p. 224, homologizes these gilis with those of the genus Asterope, supporting his view
especially by their number and position. It is, at any rate, certainly prématuré at the present
time to describe these gilis by the term „epipodial appendages“ .
Furca: —
With regard to this organ the terminology used by G. W. MÜLLER, has been adopted
in this work. Consequently the furcal claws are counted distally-proximally, contrary to the
practice of a number of other writers, e. g. G. S. BRADY. This method is necessitated partly
because in several forms these claws vary in number, when it is always the small proximal claws
that are subject to variation, and partly because they are formed ontogenetically
distally-proximally, the proximal ones not appearing until the mature stage is reached.
Frontal organ*: —
This is most frequently termed in the present work ,,the rod-shaped organ“, on
accoimt of its shape.
With regard to other organs the terminology used by G. W. MÜLLER has been
adopted in this work.
Terminology of the larval stages: —
By Stage I in the present work is meant the oldest larval stage, the stage next to
the mature stage. The stage immediately preceding Stage I is called Stage II, the stage
immediately preceding Stage II is Stage III, and so on.
This terminology has not been used by previous writers. C. CLAUS and G. W. Müller
dénoté the youngest freely living larval stage by Stage I, the subséquent stage by Stage II,
and so on. This terminology seems inconvénient on account of the deficiency of our present
knowledge of the post-embryonal development of this group, especially with regard to the
youngest larval stages. A conséquence of the employment of this terminology has been that
larval stages with the same numbers do not correspond to each other in the works of different
writers or even in different works of the same writer. Thus Stage I of the genus Conchoecia
in G, W . MÜLLER’s works of 1893 and 1894 — of which this author says, 1893, p. 376, ,,Das
erste mir bekannt gewordene Stadium, das ich geneigt bin, für das erste überhaupt zu halten“
corresponds to Stage III of the same genus in C. Claus, 1893.
* Contrary to the practice in G. \\. .Müller s works. in this tréalisé, ns in W. Giksbkecht, 1913, the nauplius
eye is not reckoned as a frontal organ (W. Giesbrecht, 1913, p. 120). G. W. Müller writes, 1912, p. 8: „Das
Frontalorgan . . . besteht aus dem dreiteiligen Medianauge und . . .
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