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SUMMARY
Gastropoda Opisthobranchia
of Iceland I. Introduction
and the Ascoglossa.
by J. fí. Sigurdsson,
Instilute of Biology, Universily of Iceland,
Grensásvegur 12, Reykjavik.
A general introduction is given to six
orders of Gastropoda Opisthobranchia
which have representatives in Icelandic
waters. A more detailed account is given of
the Order Ascoglossa of which three species
belong to the Icelandic fauna, two of which
Alderia modesta (Lovén) and Limapontia
senestra (Quatrefages) have not been
recorded from Iccland before.
1. Alderia modesta was found in Iceland for
the first time as recently as 1976 at Mela-
bakkar on the coast of Faxaflói in western
Iceland by A. Ingolfsson. It has since been
found in suitable locations ranging from
Hornafjördur in Southeast Iceland to Ön-
undarfjördur in Northwestcrn Iceland. No
search has bcen made for this species on the
north or east coasts. Ingolfsson has kindly
supplied the information that A. modesta is
found in pools ranging in salinity from 6.6%
to 35% at Mclabakkar and salinity has been
measured as low as 2.4% at the saltmarsh
where it was found in Hornafjördur. Spawn
has been found from J'uly to October, in-
variably in pools on the saltmarshes. Spawn
masses up to 2 cm in length containing
approximately 5000 eggs have been found.
Diameter of Icelandic eggs is 160—170 pm,
yolk mass diametcr 90 pm. This is con-
siderably larger than has been reported
elsewhere (Thompson 1976).
2. Limapontia capitata (Muller) was collcc-
tcd at Reykjavik in the 19th century by
Japetus Steenstrup (Lemche 1938). There
are no reliable records of this species since
thcn.
3. Limaþontia senestra (Quatrefages) was
found by the author on Cladoþhora rupestris
on the lower shore at Álftanes near Reykja-
vík in 1978. The location is fully saline and
exposed to waves. Egg masses contain from 5
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