Full resolution (JPEG) - On this page / på denna sida - Sidor ...
<< prev. page << föreg. sida << >> nästa sida >> next page >>
Below is the raw OCR text
from the above scanned image.
Do you see an error? Proofread the page now!
Här nedan syns maskintolkade texten från faksimilbilden ovan.
Ser du något fel? Korrekturläs sidan nu!
This page has never been proofread. / Denna sida har aldrig korrekturlästs.
Entomoconchus M’Cov, form a special family, Entomoconchidae, by the side of the families
Cypridinidae and „Gonchoeciadae“ within the section Myodocopa. G. S. BRADY and A. M.
Norman, in their work of 1896, p. 628, write of this genus that it „probably will be found to
belong to the group Myodocopa“. When in 1902 a, p. 188 G. S. Brady established the genus
Codonocera he wrote the genus Heterodesmus as a synonym: ,,? Heterodesmus Brady.“ Since
then — if we are to judge from the literature — this form has never been found again, nor have
any new species been described that can be referred with certainty to this genus.
On account of the incompleteness of the description G. W. MÜLLER, when revising the
< Istracod group, did not tliink it possible to place this genus systematically. In his synoptic
work of 1912, p. 398 he puts it under the heading of „Ostracodum genera et species
incertae s e d i s“; in doing so he wished to point out that it is even impossible to decide
which main group within the Ostracoda this genus belongs to. Other a uthors who deal with
this group do not touch upon this genus.
Even from the shape of the shell —- the strongly ventricose ventral margin and the
presence of a rostral incisur (the latter is, however, only very indistinctly indicated in the figure
and is not mentioned in the text) — it seems very probable that the genus Heterodesmus is to be
placed within the group Myodocopa, as G. S. BRADA’ has already done. The faet that the species
in question was caught swimming freely in the sea, ,,taken in the towing-net“, also supports
this supposition. It also seems to me very probable that this genus is closely connected
with the sub-genus Siphonostra established by me above. This is supported, above all, by the
faet that, to judge from figs. 6 a, g and h, H. Adamsi has a shell that is developed
postero-dorsally into a siphon (presumably) of quite the same type as that of the last-mentioned
sub-genus. The hinge of the shell points to the same conclusion. The question as to whether
the two forms are distinguished from each other generically or not can, of course, not yet be
decided, though it does not seem impossible that at some future time it will appear that they
ought to be included in the same sub-genus.
With regard to G. S. Brady’s assump tion that Heterodesmus is a synonym of the genus
Codonocera I may merely point out liere that — to judge from the literature — the shell of the
latter genus is not developed as a siphon posteriorly.
Siphonostra spinifera n. sp.
Descript ion: — F e m a 1 e : —
Shell: — Length, 2,32 mm. Length: height, about 1,8 : 1; length : breadth, about
1,75 : 1. Seen from the side (fig. 3) it is very elongated with the greatest height at
about a third of the distance along the shell; the anterior part is slightly larger than the posterior
one. The dorsal and ventral margins are of about the same shape, uniformly arched, the
arcuation is moderately strong; they join the anterior and posterior margins without corners.
The posterior part of the shell is, at about half the height of the shell, drawn out into a rather
wide process cut abruptly off distally and directed obliquely upwards; the ventral margin of
<< prev. page << föreg. sida << >> nästa sida >> next page >>
