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Synonymy.
Réduction oj the
third jurcal claw.
Time oj occurrence.
Specimens jrom
different regions.
Parasites of this
species.
Phenomcna oj
parasitism.
The form tliat is dealt with by G. O. SARS, 1865, p. 104, is also rather
incom-pletely described. As, in addition, the description is not accompanied by illustrations, this
form should really be denoted as unidentifiable. The description given by me above is, however,
from specimens — found at Lofoten — that this investigator had determined to be Cypridina
norvegica. For this reason I have considered it best to look upon all the information given
bv this writer about C. norvegica as really referring to the species dealt with liere, although
all the separate statements have not been tested by me.
Whether the form described by G. S. BRADA and A. M. NORMAN, 1896, p. 647, under
the name of Cypridina norvegica is to be considered as identical with the species dealt with
above, is not quite certain, at least if attention is only paid to the description and figures.
Differences are found both in regard to the shell and the furca and limbs, as is soon shown by
even a superficial comparison between the two descriptions. In spite of this I have included
this form as a synonym of the species dealt with above, because G. S. BRADY and A. M. NORMAN
have, if we judge from the text, based their description on specimens from the coast of Norway
and because I knew that these writers often take very little care about the correctness of their details.
On the other hånd it did not seem proper to me to include as synonyms Cypridina norvegica
A. M. Norman, ises, p. 439, 1869, pp. 256, 257, 260, 295, 1891, pp. 119, 121; G. S. BRADY and
I). Robertson, 1872, p. 70 and C. H. Ostenfeld and C. Wesenberg-Lund, 1909, p. 113, because
these statements were not accompanied by any figures or information at all to veri fy tkem.
The réduction of the third furcal claw, though only slight, ought perhaps to be specially
mentioned; it has a certain interest because it is just this claw that is exceedingly reduced
in another species of this sub-genus, F. Vanhöffeni (G. W. Müller).
Sexually mature males and females with embryos were found both on the 18th of May
and the 5th of August on the West Coast of Sweden and between the 3rd and llth of September
in Trondhjem Fjord.
There was no difference in size between the specimens from northern regions, the Lofoten
Islands, and those from more Southern places, Koster Fjord. From both localities comparatively
large as well as comparatively small specimens were recorded.
Especially conspicuous was a parasitic I s o p o d, Cyproniscus cypridinae (G. O. SARS),
concerning wliich I will only quote G. O. Sars’s statement, 1899, p. 235: ,,I have not infrequently
found this interesting form o ff the Lofoten Islands and at Bodö and Selsövig, infesting Cypridina
norvegica Baird.......The parasite, when fully developed, is easily observable through the
semipellucid valves of the Cypridina, always occupying the place where otherwise the ova and
embryos of the latter are carried during their development. Occasionally the parasite also
occurs on male Cypridinae-, but in no instance have I found it in this case fully developed, and
it is very probable that under such circumstances it does not ever reach maturity.“ This parasite
occurred on about 30 per cent. of the specimens of the above species recorded from the Trondhjem
Fjord and the Koster Fjord, but curiously enough no specimen of it was found on the specimens
of Cypridina from the Lofoten Islands that I have examined.
The specimens of this species that are mentioned below as having been caught in
Trond-hjem Fjord were all found in the cloaca and uterus oîEtmopterus spinax (Linné). According
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