TERRESTRIAL MOLLUSCA INHABITING SOCIETY ISLANDS. 33 
This, the largest species inhabiting the group, is comparatively rare, and is peculiar 
to the above island, where it was found about 900 feet above sea-level. 
Its most obvious characters are its large size, wide perspective umbilicus, depressed 
form, numerous whorls, subangulate periphery and numerous lamine. 
Genus LIBERA, Garrett. 
There exists a good deal of confusion in regard to the synonymy of the Society 
Island species of Libera, caused, no doubt, by the intermixture of specimens collected 
in different localities. Such, I am sure, was the case with the examples collected by 
the naturalists of the United States Exploring Expedition, which were described by 
Dr. Gould under the name of Helix bursatella and varieties. The numerous specimens 
collected by the writer at Tahiti and Moorea, in 1861, passed into Mr. Pease’s posses- 
sion, and, like Gould (with one exception), he regarded them as a single variable 
species. 
In my subsequent explorations of the above two islands I made a careful study of 
the specimens gathered in the different valleys on each island, and am thoroughly 
convinced that there are several valid species included in Gould’s 1. bursatella and 
varieties. In fact the various species are as well defined and distinct from each other 
as the majority of Helices, and, so far as I know, do not intergrade with each other. 
It is particularly noteworthy that each species has its special habitat; some restricted 
to a single valley, and others ranging throughout two or more valleys, but never 
intruding on each other’s localities. The Tahiti species are specifically distinct from 
the Moorea shells, and both differ from those inhabiting the Cook’s group. It isa 
noteworthy and remarkable fact that this genus, which in this group is restricted to 
Tahiti and Moorea, is represented in all the leeward islands by the allied genus 
Endodonta. 
Dr. Pfeiffer appears to have been somewhat bewildered in his treatment of the 
various species described by Gould, Reeve, Hombron and Jacquinot, and himself. In 
the first volume of his ‘‘ Monographia Heliceorum,” he simply repeats Gould’s descrip- 
tion and varieties. In his third volume he restricts and redescribes Gould’s species, 
and adds to its synonymy H. turricula, Homb. and Jacq., and removes Gould’s var. b, 
together with H. excavata, Homb. and Jacq., to the synonymy of H. Jacquinoti, Pfr., 
and cites Tahiti and Marquesas as habitats. On the same page he describes H. 
cavernula, Homb. and Jacq., with H. coarctata, Pfr.,as a synonym. In the fourth 
volume he eliminates H. turricula from the synonymy of 1. bursatella, and removes 
H. excavata from H. Jacquinoti to Gould’s species. He also shifts H. cavernula, 
Homb. and Jacq. (not of Pfr.), to the synonymy of H. Jacquinoti. His H. cavernula 
(not of Homb. and Jacq.) he refers to H. streptaxon, Rve., and quotes H. coaretata, 
H. turricula and Gould’s H. bursatella, var. 6 and c, as synonyms of Reeve’s shell. In 
the fifth volume he doubts ZZ. cavernula, H. and J., being synonymous with H. Jacqui- 
