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S e v e n t h 1 i m b: — This shows no dimorphism and varies very slightly in this group.
It seems to serve chiefly as a sort of cleaning organ, but its effectiveness does not seem to be
very great; cf. G. W. Müller, 1894, p. 73; it is probably to be taken as a very much reduced
organ. Like the cleaning limb in the Cypridiniformes it is placed fairly high up on the side
of the body, somewhat behind the sixth limb. Wiren in a position of rest it points in most cases
obliquely upwards and backwards. It is very small and consists of quite a short, two-jointed
or un jointed stem, which grows somewhat narro wer distally and is furnished with simple,
moderately strong musculature. (The question of the morphological value of this stem seems
at present impossible to decide with certain ty; does it correspond to the protopodite + the
exopodite or only to the exopodite? See p. 50 above. The latter alternative seems most
probable to me.) The epipodial appendage and the endopodite are quite absent.
The proximal joint, which is somewhat elongated, is quite without bristles. The end joint is
short and has two well-developed distal* bristles.
The b r u s h - s h a p e d o r g a n is quite absent.
F urca: —This is always well developed, rather large and powerful with short, broad
lamelliform rami, armed with a varying number of claws: from two to eight were observed.
The heart is always developed?
Se nsory organs — Quite blind forms** ; no traces of either lateral eyes or a Nauplius eye,
have hitherto been found. (G. O. SARS pointed out in his work of 1865, pp. 116—117, the following
facts: „In basi vero antennarum superiorum corpuscula adsunt pluria lentiformia, irrégularité!’
acervatis sed semper in stratu distincte nervoso collocata pigmento vero nullo circumdata,
quae organa quamquam imperfecta visus esse videntur.“ In this writer’s work of 1887, p. 70,
too, the occurrence of similar bodies is pointed out „en Del eiendommelige lindseagtige Legemer,
der maaske tor ansees for et Slags ufuldkomne Synsapparater“*** in the proximal part of the
first antenna in a couple of the Scandinavian species of the genus Conchoecia. This observation
is repeated by G. S. Brady and A. M. NORMAN, 1896, p. 685; they point out that the first joint
of the first antenna in Conchoecia elegans G. 0. Sars „shows, irregularly scattered near its surface,
a number of lenticular bodies overlaying patches of red pigment, perhaps rudimentary visual
organs“. I have found similar patches in the first antennae not only of C. elegans and C. borealis,
the species referred to by G. O. Sars, but of a great number of species of this genus; in exceptional
cases these are also found in other places, e. g. on the protopodite of the second antenna in, for
instance, C. hettacra G. W. Müller. It seems very uncertain whether these bodies are visual
organs but it seems best not to make any statement as to t-heir morphological value before
any experiments at all have been carried out. In any case such statements could only be very
uncertain.)
A rod-s haped organf is developed in most cases.
* Only in exceptional cases, in single specimens, are three bristles found.
** For .1. D. Daïna’s establishing of eyes (1852, p. 1297) see p. 562 below.
*** ,,Some peculiar lenticular bodies, which are perhaps to be interpreted as a sort of imperfect visual organs.“
t G. W. Muller proposes (1894, p. 163) as the „wahrscheinlichste, oder, wenn man will, am wenigsten
unwahrscheinliche“ explanatidn of the rod-shaped organ in the Halocyprids that it is a light-percipient organ,
not, however, for forming images, but only for „eine Unterscheidung von hell und dunkel“,
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