Treasury Is. Mollusca — Dell 
429 
solomonensis , and Palaina gardneri , very prob- 
ably occur elsewhere but have not been col- 
lected. Of the 19 species recorded here, the 
following eight have a wide range of distribu- 
tion throughout the group: Papusuccinea sim- 
plex, Pupina solomonensis , Sturanya modesta , 
Palaeohelicina egregia, Pseudocyclotus levis , Lepto- 
poma vitreum , Omphalotropis nebulosa , and Opeas 
gracilis. Two species, Orpiella treasuryensis and 
Partula sp. appear to have affinities with the 
fauna of the southern Solomons. A significant 
three species have a distribution restricted to 
the islands surrounding Bougainville Strait. 
Thus Dendrotrochus cineraceus cineraceus is, as 
far as is known, confined to Choiseul, Short- 
land, and Bougainville, whereas Placostylus 
founaki and Papuina gamelia both apparently 
extend to Bougainville and as far south as 
Ysabel. However, neither of these species 
reach Vella Lavella, Gizo or New Georgia 
where the genera are represented by very dif- 
ferent species. The land snail relationships 
appear to extend from Bougainville via Short- 
land and Treasury, Choiseul and Ysabel, but 
not via Vella Lavella to New Georgia. This 
point will be dealt with more fully on a 
later occasion. 
REFERENCES 
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Dell, R. K. 1955. The land Mollusca of 
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