?0 DISCOVERY REPORTS 



Family Trichotropidae 



There are four endemic southern high-latitude genera in this family, clearly related to the boreal 

 genera, Trichotropis and Torellia. The range of the four southern genera is : 



(i) Antitrichotropis : Antarctic, Palmer Archipelago to Ross Sea. 



(2) Trichoconcha : Antarctic, South Georgia to Ross Sea. 



(3) Neoconcha : Ross Sea. 



(4) Discotrichoconcha : Palmer Archipelago. 



Familes Crepidulidae and Calyptraeidae 



The genus Crepipatella is of West American origin, dilatata occurring from the west coast of South 

 America and the Magellan Province, and lingulata from the Bering Sea to Panama. 



The genus Trochita is West American also, ranging from Panama to the Magellan Province and 

 occurring also at South Georgia. The simplification of the septum in the South Georgian species 

 suggests that it and the New Zealand Zegalerus may have had a common origin in the south. 



Family Struthiolariidae 



In the systematic section I suggest that the only living southern high-latitude Struthiolarid genus, 

 Perissodonta, is identical with a South American Oligocene group (Struthiolarella). The known range 

 of the Struthiolariidae is: Patagonia (Oligocene), South Georgia and Kerguelen Island (Recent), 

 Perissodonta; New Zealand, Conchothyra (Upper Cretaceous), Perissodonta {Struthiolarella minor 

 (Marshall, 1917)) (Danian, Upper Cretaceous), Monalaria (Lower Tertiary), Callusaria (Middle and 

 Upper Tertiary), Struthiolaria (Middle Tertiary to Recent), Pelicaria (Upper Tertiary to Recent) ; 

 Southern Australia, Tylospira, Upper Tertiary to Recent. 



The family seems to have had its origin in the Jurassic to Recent Aporrhaidae, which are of northern 

 hemisphere origin, to have spread down the Americas to Patagonia and finally reached South Georgia, 

 Kerguelen, New Zealand and Australia by shallow-water extensions from Antarctica. The present 

 discontinuous distribution of Struthiolarids is evidently the result of extinctions over much of the 

 probable former range of the family. 



Family Cymatiidae 



The genus Fusitriton has been referred to in the previous section on ' Bipolarity ' and is dealt with 

 more fully in the systematic section. Its range is from Japan via the Aleutian Chain, the western coast 

 of the Americas, Falkland Islands, South Africa, Marion Island via the Atlantic-Indian Ocean cross- 

 ridge, New Zealand and southern to eastern Australia. 



Family Buccinulidae 



The southern whelks are apparently related to the northern Neptuniidae rather than to the northern 

 Buccinidae. There is a considerable radiation of southern generic groups, even more so than in the 

 Trochidae. The distribution of these genera is as follows: 



(1) Pareuthria. Magellan, Davis Sea and Campbell Island, New Zealand Subantarctic. 



(2) Tromina. Magellan, and Clarence Island, South Shetlands. 



(3) Notoficula. Bouvet Island and Falkland Islands. Atlantic-Indian Ocean cross-ridge. 



(4) Falsimohnia n.g. South Georgia and Kerguelen Island. 



(5) Glypteuthria. Magellan and South Africa. Atlantic-Indian Ocean cross-ridge. 



(6) Chlanidota. South Shetlands, South Orkneys, South Georgia, Bouvet Island, Kerguelen Island 

 and Cape Adare. 



(7) Pfefferia. South Georgia. 



(8) Neobuccinum. Graham Land to Ross Sea and Kerguelen Island. 



