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R. K. DELL
The great complex of forms usually classified in the two families
Cominellidae and Buccinulidae, but rather doubtfully separable, supply
the best example of explosive radiation in the Antarctic mollusca. The
genus Pareuthria with many Subantarctic and southern South American
species has one representative, P. innocens (Smith), widely distributed
in East Antarctica. The genus Tromina has four species distributed in
the Magellan region and on the Patagonian Shelf and one at the South
Shetlands. The single species in the monotypic genus Falsimohnia,
F. albozonata, has been recorded from Kerguelen and South Georgia.
The genus Chlanidota provides an interesting example of specific
radiation in itself (Fig. 11). Eight species are known, six of them confined to limited areas of the Scotia Arc and Bouvet Island respectively,
one from East Antarctica, and one extending from Kerguelen to East
Antarctica.
The monotypic genus Chlanijicula is known only from East Antarctica while Notojicula, another monotypic genus is apparently circumAntarctic. The genus Pfevfferia with its three species is endemic to
South Georgia. Chlanidotella with its single species C . modesta is confined also to South Georgia. The species Neobuccinum eatoni (Smith) is
one of the most widely distributed Antarctic gastropods occurring right
around the Continent, and at Kerguelen and Heard Islands.
The genus Bathydomus is also an endemic genus, one of its four
species being recorded from shallow water off Enderby Land, the other
three from peripheral areas in depths from 2 515 to 3 423 m. Fusinella,
another monotypic genus, is confined to Kerguelen Island, while the
peculiar Cavineptunea is endemic to South Georgia. Probuccinum has
seven Antarctic species and a single Subantarctic representative.
Proneptunea occurs on Kerguelen (one species) and at South Georgia
(two species). The genus which outweighs all the rest in numbers is
Prosipho with 28 Antarctic and five subantarctic species. This latter
genus produces several species which are coiled in a sinistral spiral in
the normal condition.
The family Muricidae has strong representation in the genus
Trophon with large sized species in the Subantarctic and with a few
exceptions smaller sized species in the Antarctic.
The family Volutidae is at present known only by the genus Harpovoluta, an extremely thin-shelled form, with two species and subspecies from the Antarctic shelf. Two poorly known genera Guivillea
and Provocator occur in adjoining deep-sea areas. Other volute genera
are represented in deep-water collections made by the Eltanin.
The genus Paradmete with four species confined to the AntarcticSubantarctic is the only member of the Volutomitridae.
R. K. DELL
The great complex of forms usually classified in the two families
Cominellidae and Buccinulidae, but rather doubtfully separable, supply
the best example of explosive radiation in the Antarctic mollusca. The
genus Pareuthria with many Subantarctic and southern South American
species has one representative, P. innocens (Smith), widely distributed
in East Antarctica. The genus Tromina has four species distributed in
the Magellan region and on the Patagonian Shelf and one at the South
Shetlands. The single species in the monotypic genus Falsimohnia,
F. albozonata, has been recorded from Kerguelen and South Georgia.
The genus Chlanidota provides an interesting example of specific
radiation in itself (Fig. 11). Eight species are known, six of them confined to limited areas of the Scotia Arc and Bouvet Island respectively,
one from East Antarctica, and one extending from Kerguelen to East
Antarctica.
The monotypic genus Chlanijicula is known only from East Antarctica while Notojicula, another monotypic genus is apparently circumAntarctic. The genus Pfevfferia with its three species is endemic to
South Georgia. Chlanidotella with its single species C . modesta is confined also to South Georgia. The species Neobuccinum eatoni (Smith) is
one of the most widely distributed Antarctic gastropods occurring right
around the Continent, and at Kerguelen and Heard Islands.
The genus Bathydomus is also an endemic genus, one of its four
species being recorded from shallow water off Enderby Land, the other
three from peripheral areas in depths from 2 515 to 3 423 m. Fusinella,
another monotypic genus, is confined to Kerguelen Island, while the
peculiar Cavineptunea is endemic to South Georgia. Probuccinum has
seven Antarctic species and a single Subantarctic representative.
Proneptunea occurs on Kerguelen (one species) and at South Georgia
(two species). The genus which outweighs all the rest in numbers is
Prosipho with 28 Antarctic and five subantarctic species. This latter
genus produces several species which are coiled in a sinistral spiral in
the normal condition.
The family Muricidae has strong representation in the genus
Trophon with large sized species in the Subantarctic and with a few
exceptions smaller sized species in the Antarctic.
The family Volutidae is at present known only by the genus Harpovoluta, an extremely thin-shelled form, with two species and subspecies from the Antarctic shelf. Two poorly known genera Guivillea
and Provocator occur in adjoining deep-sea areas. Other volute genera
are represented in deep-water collections made by the Eltanin.
The genus Paradmete with four species confined to the AntarcticSubantarctic is the only member of the Volutomitridae.