ANTARCTIC BENTHOS
117
recently given an account of the distribution of selected groups. Kott’s
monograph describes, figures and discusses 122 species of both Antarctic
and Subantarctic forms. Her bibliography is particularly full for
ascidians in general, as well as Antarctic species.
Kott analysed the geographic and bathymetric distribution of
Antarctic ascidians in relation to her own biogeographic scheme for the
Antarctic which although claimed as being a combination of Powell
(1965) and Andriashev (1965), is in fact almost the same as that proposed by Knox. It is, however, difficult to know whether Kott includes
the Antarctic PeninsuIa in the Continental Province or the South
Georgian Province, or South Georgia in the South Georgian Province
of the Antarctic Subregion or in the Magellanic Province of the Subantarctic Subregion. Much more is involved in this issue than a mere
problem of semantics, since Kott’s study is one of the few modern
monographs of a complete group based upon practically all the most
important recent collections.
In another publication in the same year, Kott (1969b) presented a
biogeographical scheme which resolved these difficulties. Here the
Antarctic region (south of the Antarctic Convergence) is divided into a
Continental Province (the circumpolar region near the continent) and a
South Georgian Province (‘I the Antarctic Peninsula and the Subantarctic (sic) islands along the Scotia Ridge to South Georgia ”). The Subantarctic Region is defined as being between the Subtropical and the
Antarctic Convergences. Kott finds some evidence for an “ eastern ”
district of the Continental Antarctic Province, in that a few species are
to date recorded only from the Enderby and Victoria quadrants.
Kott (1969a, 207) identifies the following groups of ascidians based
upon their distribution.
1. Species distributed in the ‘‘ antarctic subregion ” (the “Antarctic ” of the present work) reaching at least to the South Shetlands and
often extending north into the subantarctic. Most of the species in this
group are circumpolar, and many are circumpolar in the Subantarctic.
They occur over most of the shelf and into the deeper waters of the
slope. With few exceptions they have a minimum depth range of 400 m.
Kott suggests that their persistence in antarctic waters may well be
due to their wide depth tolerance allowing them to escape the effects of
glaciation on the shelf. Kott considers that some 30 species fall into
this group.
2. Species with a limited distribution in the “ antarctic subregion ”
(Antarctic). The occurrences of these eight species are based on comparatively few records. They all also have a limited bathymetric
range, and may well represent recent derivatives. Only one species,
117
recently given an account of the distribution of selected groups. Kott’s
monograph describes, figures and discusses 122 species of both Antarctic
and Subantarctic forms. Her bibliography is particularly full for
ascidians in general, as well as Antarctic species.
Kott analysed the geographic and bathymetric distribution of
Antarctic ascidians in relation to her own biogeographic scheme for the
Antarctic which although claimed as being a combination of Powell
(1965) and Andriashev (1965), is in fact almost the same as that proposed by Knox. It is, however, difficult to know whether Kott includes
the Antarctic PeninsuIa in the Continental Province or the South
Georgian Province, or South Georgia in the South Georgian Province
of the Antarctic Subregion or in the Magellanic Province of the Subantarctic Subregion. Much more is involved in this issue than a mere
problem of semantics, since Kott’s study is one of the few modern
monographs of a complete group based upon practically all the most
important recent collections.
In another publication in the same year, Kott (1969b) presented a
biogeographical scheme which resolved these difficulties. Here the
Antarctic region (south of the Antarctic Convergence) is divided into a
Continental Province (the circumpolar region near the continent) and a
South Georgian Province (‘I the Antarctic Peninsula and the Subantarctic (sic) islands along the Scotia Ridge to South Georgia ”). The Subantarctic Region is defined as being between the Subtropical and the
Antarctic Convergences. Kott finds some evidence for an “ eastern ”
district of the Continental Antarctic Province, in that a few species are
to date recorded only from the Enderby and Victoria quadrants.
Kott (1969a, 207) identifies the following groups of ascidians based
upon their distribution.
1. Species distributed in the ‘‘ antarctic subregion ” (the “Antarctic ” of the present work) reaching at least to the South Shetlands and
often extending north into the subantarctic. Most of the species in this
group are circumpolar, and many are circumpolar in the Subantarctic.
They occur over most of the shelf and into the deeper waters of the
slope. With few exceptions they have a minimum depth range of 400 m.
Kott suggests that their persistence in antarctic waters may well be
due to their wide depth tolerance allowing them to escape the effects of
glaciation on the shelf. Kott considers that some 30 species fall into
this group.
2. Species with a limited distribution in the “ antarctic subregion ”
(Antarctic). The occurrences of these eight species are based on comparatively few records. They all also have a limited bathymetric
range, and may well represent recent derivatives. Only one species,