46
R. K. DELL
Antarctic zones and, in considering endemism, they referred to both as
the one zoogeographical area.
The genera Plumularia (with 18 species), Campanularia (with 15
species) and Sertularella (with 40 species) are extremely well represented
although the genera Sertubria and Thuiaria which are the predominant
genera in the corresponding zones of the Northern Hemisphere are
poorly represented in the Antarctic.
Some species appear to be circumpolar in distribution and confined
to the Antarctic in the restricted sense, e.g. Opercularella belgicae
(Hartlaub), Stegella grandis (Hickson and Gravely), Sertularella glacialis
Jiiderholm, Oswaldella bifurm (Hartlaub), and 0. billardi Briggs.
Hydroids often have a wide distribution pattern and some cosmopolitan
species extend into Antarctic waters, e.g. Sertularella polyzonias (Linnaeus), S. tricuspidata (Alder), Pilellum serpens (Hassal), and Lafoea
fruticosa (Sars).
In parts of the Ross Sea hydroids appear to be well developed and
large clumps of various species are encountered. These species forming
large clumps include Halecium arboreum Allman, Sertularella spiralis
Hickson and Gravely, 8. plectilis Hickson and Gravely, Dictyocludium
ficscum Hickson and Gravely and Plumularia glacialis Hickson and
Gravely (Hickson and Gravely, 1907).
A small mud-dwelling, solitary hydroid Boreohydra simplex Westblad was described from off the Scandinavian Atlantic coasts and subsequently recorded from off Iceland and the English coast. It then turned
up from mud samples collected off South Georgia (Westblad, 1952).
This distribution pattern cannot be given too much weight until it has
been searched for more carefully in intervening localities.
6. Stylasterina
The Stylasterina, one of the two orders of hydrozoan corals, form a
rather obvious component of Antarctic benthos. They have been
studied by Marenzeller (1903), Broch (1951), Boschma (1966), and
Eguchi (1964). A recent summary on the distribution and relationships
of the Antarctic fauna has been given by Boschma and Lowe (1969).
These two authors find that a distinctive fauna inhabits the AntarcticSubantarctic area. Unfortunately they take the northern limits of the
Subantarctic considerably farther to the north than would most biogeographers, including the coastal waters of New Zealand, and even
considering the Kermadec Islands, " in the border region of the Subantarctic". The Kermadec Group is essentially an outlier of the
tropical Indo-Pacific fauna, with outliers of the tropical reef corals.
When therefore they speak of 15 of the 19 Antarctic-Subantarctic
R. K. DELL
Antarctic zones and, in considering endemism, they referred to both as
the one zoogeographical area.
The genera Plumularia (with 18 species), Campanularia (with 15
species) and Sertularella (with 40 species) are extremely well represented
although the genera Sertubria and Thuiaria which are the predominant
genera in the corresponding zones of the Northern Hemisphere are
poorly represented in the Antarctic.
Some species appear to be circumpolar in distribution and confined
to the Antarctic in the restricted sense, e.g. Opercularella belgicae
(Hartlaub), Stegella grandis (Hickson and Gravely), Sertularella glacialis
Jiiderholm, Oswaldella bifurm (Hartlaub), and 0. billardi Briggs.
Hydroids often have a wide distribution pattern and some cosmopolitan
species extend into Antarctic waters, e.g. Sertularella polyzonias (Linnaeus), S. tricuspidata (Alder), Pilellum serpens (Hassal), and Lafoea
fruticosa (Sars).
In parts of the Ross Sea hydroids appear to be well developed and
large clumps of various species are encountered. These species forming
large clumps include Halecium arboreum Allman, Sertularella spiralis
Hickson and Gravely, 8. plectilis Hickson and Gravely, Dictyocludium
ficscum Hickson and Gravely and Plumularia glacialis Hickson and
Gravely (Hickson and Gravely, 1907).
A small mud-dwelling, solitary hydroid Boreohydra simplex Westblad was described from off the Scandinavian Atlantic coasts and subsequently recorded from off Iceland and the English coast. It then turned
up from mud samples collected off South Georgia (Westblad, 1952).
This distribution pattern cannot be given too much weight until it has
been searched for more carefully in intervening localities.
6. Stylasterina
The Stylasterina, one of the two orders of hydrozoan corals, form a
rather obvious component of Antarctic benthos. They have been
studied by Marenzeller (1903), Broch (1951), Boschma (1966), and
Eguchi (1964). A recent summary on the distribution and relationships
of the Antarctic fauna has been given by Boschma and Lowe (1969).
These two authors find that a distinctive fauna inhabits the AntarcticSubantarctic area. Unfortunately they take the northern limits of the
Subantarctic considerably farther to the north than would most biogeographers, including the coastal waters of New Zealand, and even
considering the Kermadec Islands, " in the border region of the Subantarctic". The Kermadec Group is essentially an outlier of the
tropical Indo-Pacific fauna, with outliers of the tropical reef corals.
When therefore they speak of 15 of the 19 Antarctic-Subantarctic