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 perspecti^-e umbilicus, depressed 
form, numerous whorls, subangulate periphery and numerous lamina?. 
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. Gonld under the name of Helix hursatella and varieties. The numerous specimens 
collected by the writer at Tahiti and Moorea, in 1861, passed into Mr. Pease’s possi's- 
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 Goidd’s If. hursatella 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 lalley, and others ranging throughout two or more valleys, but never 
intrnding on each otlier’s localities. The Tahiti species are specifically distinct from 
the Moorea shells, and both differ from those inhabiting the Cook’s group. It is a 
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 gtmus 
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 Gotild’s de.scrip- 
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. h, 
together with H. excavata, Homb. and Jacq., to the synonymy of II. Jaxqninofi, Pfr., 
and cites Tahiti and Marquesas as habitats. On the same page he describes If. 
cavermda, Homb. and Jacq., with H. coarctata, Pfr., as a synonym. In the fourtli 
volume he eliminates H. turricida from the synonymy of II hursatella, and removes 
II. excavata from H. Jacquinoti to Gould’s species. He also shifts II. cavernida, 
Homb. and Jacq. (not of Pfr.), to the synonymy of H. Jacquinoti. His H. carcriiida 
(not of Homb. and Jacq.) he refers to II. streptaxon, Rve., and quotes II. coarctata, 
H. turricida and Gould’s H. hursatella, var. h and c, as synonyms of Reeve’s shell. In 
the fifth I'olume he doubts H. cavernula, H. and J., being synonymous with II. Jacqui- 
