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Are we to accept the homologization carried out by G. W. MULLER?
In answering this question I shall leave the Cypridinids, Halocyprids
and P o 1 y c o p i d s out of considération and turn to the groups, on whose number of joints
G. W. MULLER has obviously based the assumption mentioned above. Macrocypris, the genus
that is considered as the most primitive among the C y p r i d s, is characterized by a
four-jointed endopodite. Its second joint is comparatively long and has on the posterior edge,
proximally of the middle, one or a couple of bristles, on the anterior edge, near the third joint,
two bristles situated close to eacli other. The third joint is comparatively short and is moved
by two muscles, a flexor and an extensor, both with a proximal attachment situated proximally
in the second joint; this joint is always armed disto-anteriorly with a number of long, powerful
claws. The fourth joint is small, issuing at about the middle of the posterior side of the third
joint; it is moved by only one muscle, which has its proximal attachment proximally in the
second joint; and it is armed distally with several bristles, one of which is a sensory bristle.
In other genera belonging to the family Cypridae the state of affairs is often somewhat different.
The postero-proximal bristle of the second joint is almost always lacking, but, on the other
hand, this joint almost always has, as in Macrocypris, on the anterior edge two* bristles situated
close toge ther; only in exceptional cases does one of these bristles seem to be absent. In some
species the boundary between the second and third joints has more or less completely disappeared.
In a number of these forms the two muscles which we found moved the third joint in the genus
Macrocypris are missing; in others, however, they can be found; distally-anteriorly this joint,
as in Macrocypris, always has powerful, claw-like bristles. The fourth joint may be more
or less completely reduced in a number of species, but even in those forms in which this joint
has quite disappeared it always seems possible to distinguish by their position the bristles that
belong to this joint from those that belong to the original third joint, as they are situated
distally-posteriorly on the end joint and are separated from the bristles of the original third
joint by a swelling in the chitinous wall of the joint; in some forms a distinct gap can also be
observed between these two groups of bristles. In the family Nesideidae we find the
follow-ing state of affairs: All the three recent genera of this family that have been described so far,
Nesidea, Bythocypris and Anchistrochdes, have a four-jointed endopodite, of about the same
type in all of them. The genus Nesidea (cf. G. W. MUller. 1894, pl. XV, fig. 29): The second
joint is moderately long and has only one or a few bristles situated postero-distally. The third
joint is relatively long; it is not moved by special muscles and has, among other things, two
bristles situated close together on the anterior edge a short distance from the distal boundary;
distally-anteriorly this joint has no bristles at all. The fourth joint is short and is moved by
two muscles, a flexor and an extensor, both having a proximal attachment proximally on the
second joint; it is provided with five bristles, which, at least in a number of species, are situated
in two groups, as I have had an opportunity of observing myself when investigating a couple
*) G. W. Müller states, 1894, p. 40 that the Cyprids always have a single bristle at this place. „Das
2. Glied des Innenastes .... trägt constant eine kleine Borste am dorsalen Rand“; two bristles, are, however, drawn
in the figures of several species belonging to this group that this author has given in this work. The statement made
above is based on observations of a large number of species investigated by me.
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