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Important
characters.
Tvpe 1: All the furcal clavvs are well defined from the lamellae and deorease uniformly in
length and strength the more proximally they are situated. — This type is found in C. (C.) acuminata
(O. W. Müller! and C. (C.) natans (G. S. Brada). Cf. G. \Y. MÜLLER, 1906 b. pi. 11. fig. 3.
Tvpe II: The second furcal claw is united witli the lamella, the others are all well defined
proximally: all the claws decrease uniformly in length and strength the more proximally they are
situated, sometimes, perhaps, the third of them is somewhat wealcer than one would expect from
its position. — This tvpe is found in C. ( (’.) dentata (G. \\. M i ’LLER), C. (( ’.) tner nus (G. \Y . MÜLLER)
and C. (C.) sinuosa (G. W. MÜLLER). Cf. G. V. Müller, 1906 b, pi. II., ligs. 21, 10 and 11.
Tvpe III: The second furcal claw is united to the lamella, all the others are well defined
proximallv; all the claws decrease fairly uniformly in length and strength the more proximally
they are situated, with the exception of the third. which is considerably shorter and weaker
than one would expect from its position. — This type is found in C. (C.) amphiaeantha (G. W.
Müller). Cf. this author, 1906 b, pl. III., fig. 11.
Type IV: The second and fourth furcal claws are united to the lamella, all the others
are well defined proximally; all the claws decrease uniformly in length and strength the more
proximallv they are situated, with the exception of claw no. 3, which is considerably shorter
and weaker than one would expect from its position. — This type is found in the females of
C. (C.) serrata (G. W. MÜLLER) [— C. (C.) lepidophorg (G. YT. MÜLLER), cf. below, note on
(’. (C.) serrata, var. affirmans]. Cf. G. V . MÜLLER, 1906 b. pl. III., fig. 19.
These types are found in the sub-genera Vart]ula and Siphonostra as follows:
Type I: Appears to occur in most of the species of the sub-genus Vargula, as for instance
in C. (V.) megalops; see the fig. 16 of this organ of this species in this work.
Type II: Found in Cypridina Hilgendorfi G. \V. MÜLLER, a species that is certainlv
to be referred to the sub-genus Vargula. See G. W. MÜLLER, 1890, pi. XXVI.. fig. 1.
Type III: Found in Cypridina Vanhöffeni G. \Y. Müller, a species that certainlv
belongs to the sub-genus Vargula. Cf. G. \V. MÜLLER, 1908, pi. V., fig. 4.
Type IV: Found in the female of Cypridina (Vargula) norvegica (W. Baird); the third
furcal claw is, however, only rather slightly weakened; cf. the description of this species given
below. In addition we find this furcal type in the only representative of the sub-genus
Siphonostra. The resemblance between G. W. Müller’s dra wing of the furca for Cypridina (C.)
serrata, and the figure given below in this work of the furca in Cypridina (Siphonostra) spinifera
is really almost perfect.
The occurrence of the second, third and fourth furcal types in tliese three
subgenera can certainlv not be explained otherwise than by convergence. One can as a matter
of faet scarcely avoid the idea that in tliese groups there is to be found a „tendency“ in the
second and fourth furcal claws to unite with the lamella and in the third furcal claw to be
reduced in length and strength !
Other examples of convergence within this sub-family could be given, but the one given
a bove, which is the most striking, should, at least in this connection, be sufficient.
Among all the characters 1 have had occasion to observe those which seemed to
me the most noteworthy for the solution of this problem were the equipment on the b-
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