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distally with strong bristles; they are situated almost at right angles to eacli other, the first
endite points somewhat forward and inward, backward and outward, the second endite somewhat
forward and outward, backward and inward; their relative positions and orientation in relation
to the endopodite will be best seen from the adj oining diagram, fig. CXI, representing a horizontal
section through the left maxilla. The endite on the coxale is not inconsiderably larger than the
one on the procoxale and is weakly bifurcated distally. (This
bifurcation has been taken by several of the preceding writers
as a sign that this endite has arisen from the junction of two.
It is difficult to decide how far this assumption is justifiée!; there
are no transitional forms; the assumption, which is obviously
based on the faet that in the Gypridiniformes this limb has in
most cases three endites on these two joints, seems to me,
however, not improbable.)* The basale has no trace of any
endite. Endopodite: The first joint is comparatively
large and powerful, moderately long but broad and rather
considerably compressed at the sides. The end joint is rather
small, moderately strong and varies somewhat in shape.
For the differences between preceding writers’ ideas
about the various parts of this limb and that given above
see p. 34 above.
Fifth limb: — This varies rather slightly within this group. It seems to serve
chiefly as an organ for holding the food fast during mastication and for carrying the food to the
mouth, and perhaps as a masticatory organ, too; in addition it also seems to serve as a climbing
organ. It is situated on the side of the bocly just behincl the maxilla, at the boundary between
the hypostome and the anterior part of the bocly. It is always rather large and has comparatively
powerful musculature. It consists of a ventrally pointing protopodite, which is rather
volu-minous, comparatively elongated, unjointed or in exceptional cases more or less indistinetly
two-jointed, and which is not or only rather slightly larger than the exopodite, a moderately
large epipodial appendage developed as a vibratory plate, a very short, but rather powerful,
unjointed** endopodite, pointing forward and inward and developed anteriorly as a powerful
endite and a rather large and elongated backward pointing exopodite with three or four joints.***
Protopodite: In those cases in which this has two joints the boundary between the two
joints is often rather weakly developed and difficult to distinguish with certainty; the proximal
joint seems to correspond to the coxale or possibly the procoxale -j- the coxale, the distal joint
to the basale. The proximal part, the coxale in the forms that have a two-jointed protopodite,
is rather closely joined medially to the body and has no bristles at all. The distal part, the basale
* On the other hand il seems impossible to decide which of the two processes corresponds to the original second
e.idite and which is homologous with the original third endite. This has been done, however, by G. W. Müller,
1890 a, but without any reasons being given.
** lu a number of forms (see, for instance, fig. 27 of Conchoecia symmetrica) one can sometimes distinguish distally on
the endopodite a more or less well-developed chitinous fold. Is this to be explained as the remains of a division into joints?
* ** l n pi. VI, fig. 8, G. W. MüLLr r, 1906 a, the exopodite of the fifth limb of Thawnatocypris is drawn with four joints.
arn/.
t
through a maxilla of a form
belong-ing to the family Halocypridae;
diagrammat ic.
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