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Penis: — Although it is subject to considérable variation, this organ seems to be
formed on the same fundamental type within the whole of this sub-family. It is oval, very
strongly musculated and in most cases of considérable size. Distally it is split in the shape
of tongs; the ventral leg of the tongs is often larger than the dorsal one and is rounded distally;
the dorsal leg, which is moved by powerful muscles, varies in shape; in most cases it is
sickle-shaped, curved ventrally and rounded distally. When the dorsal leg of the tongs is pressed
against the ventral one it is situated most frequently medially to the latter. Large or small
glands are often to be found in the penis. In addition there are also at different places on this
organ large or small groups of short bristles. As a support a powerful chitinous skeleton is
developed, varying somewhat in different species. The dorsal leg of the tongs articulâtes to
the dorso-distal part of this skeleton.
Furca: — In some, presumably the majority, of the species of this group this organ
agrees in males and females, in others it shows weak or sometimes even not inconsiderable
sexual dimorphism.— The type of the lamellae varies somewhat indifferent forms, but seems
to be fairly uniform within each genus. The number of the claws is also subject to a rather
considérable variation; in some genera it seems to be quite uniform, in a number of forms it
varies somewhat, even within the species; usually the number varies between four and twelve;
sometimes, however, as in the genus Crossophorus, a somewhat larger number is found. In some
species main claws and secondary claws can be distinguished, in others it is impossible to carry
out this division. The armament of the claws seems to be very similar; at least in the species
belonging to this group that were examined by me there was very little variation shown in this
respect. Each claw is armed ventrally along the greater part of its length with two rows of
teeth situated rather close together, one row running somewhat laterally, the other somewhat
medially; on the posterior claws the teeth are somewhat weaker than on the anterior ones.
otherwise they are of about the same size and shape as each other, conical, pointed distally, smooth,
and pointing obliquely ventrally-distally. The distal teeth in the medial row of the distal (= first)
claw are, however, exceptions; these teeth differ from the others partly because they are considera bly
stronger, partly because they are displaced dorsallv and point almost straight distally; see fig. 24
of Cypridina (Macrocypridina) castanea. The distal part of the claws is sometimes smooth,
sometimes the teeth continue right out to the point of the claws; this condition is, however, often
somewhat variable even within the species. I )orsally the claws are most frequently furnished with fine
hairs or else almost smooth. Between the claws and basally on them there are no long, stift’ bristles.
The upper 1 i p is large and more or less strongly helmet-shaped. Numerous glands
open on it; theglandular field varies very much in type, often more or less distinctly tripartite.
— Similar in males and females.
The rod-shaped organ, median eye and lateral eyes vary in
development and type.
(i i 11 s are found, but only exceedingly seldom (Cypridina Hilgendorfi G. W.Mii.LER, <J).
Special terminology: — In a number of cases when, on account of striking
Agreements both with regard to number and situation, 1 thought 1 could carry out a safe
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