630 



PATAGONIAN EXPEDITIONS : ZOOLOGY. 



that South Africa has ever been connected with Antarctica and thereby 

 indirectly with southern South America. 



Non-marine mollusks having an Antarctic distribution belong to three 

 families. The evidence in each case is briefly as follows : 



I. The Buliniulida:, land snails of South American origin, of which one 

 genus [Bothriembrioti] is found in Tasmania and southwestern Australia, 

 another [Placostylus] in New Zealand, New Caledonia, the islands of 

 Melanesia and as far east as Fiji. Both of these genera are distinct from 

 South American forms, but they are undoubtedly related to the more 

 generalized of the South American genera. 



Frc. 37. 



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Distribution of the land snail family Bulimulidae. The number of genera in each area is indi- 

 cated by figures. 



The presence of Bulinmlidce in Australia and Melanesia proves that 

 the part of South America connecting with Antarctica was, or had been, 

 connected with the old Brazilian evolution center. 



2. The AmnicolidcE, a family of fresh-water snails, has one genus, 

 Potamopyrgus, in New Zealand, Tasmania and South America. Another 

 South American genus, Potanwlithus, has its nearest ally in the genus 

 Petterdiana of Tasmania and Australia. Both of these genera are exclu- 

 sively fresh-water groups. See pp. 548-550 of this report. 



