TERRESTRIAL MOLLUSC A INHABITING SOCIETY ISLANDS. tf) 
inhabited by four species found nowhere else. One (P. Ut^niata), which lias its 
metropolis in a large valley on the north coast, is, like P. OtalieiPnm, a very ^'ariable 
species, and has spread round three-fourths of the island, and, like the latter species, 
has developed local varieties which have received distinct names. P. llneata, which 
inhabits that ])art of the island not occupied by tceniata, is nearly as variable as that 
species. P. elongata, which is confined to the same portion of the island as Uneata, 
is less variable, and where it comes in contact with tceniata we find liybrids between 
the two so common as to suggest a certain degree of fertility in the intermediate forms. 
P. Jlooreana, which is always reversed, is confined to a single valley and shows but 
slight variation. 
One peculiar feature in the Tahiti and Moorea shells is the profusion of sinistral 
forms which are entirely absent from the leeward i.slands in the group. 
Huaheine, like Moorea, possesses four endemic species, all of a dift'erent type from 
those inhabiting the preceding two islands. Two (P. argata and annertens) are 
restricted to two valleys, and the latter, like P. clara, appears to be gradually becoming 
extinct. Both species are remarkably uniform in all their specific characters. On 
the contrary, the other two species (P. rosea and varia) have spread nearly all over 
the island, and are subject to considerable mutation. It is worthy of remark that 
dentated species, which are so common at all the islands except Borabora, do not occur 
on Huaheine. 
Raiatea, though only fourteen miles long and nearly half as broad, is inhabifi'd by 
twenty species of Part at a, being one-half of the number assigned to the whole grou]), 
and eighteen are found nowhere else. These, according to Dr. Hartman’s divisions, 
include not only the type, but fi^e out of his fifteen subgcncra, two ol‘ which are 
peculiar to the island. Nearly all the species are remarkably prolific, and. with few 
exceptions, are subject to greater or less variation. Ten of these varieties being local, 
have usually be('n regarded as distinct species. Six species are strictly terrestrial. 
The fine large typical P. fa^a, which has its metropolis at Utuloa on the north end of 
the island, has spread into nearly all of the valleys, and is e(pially as variable in all 
})arts of the island as in its headquarters. On the adjacent island of 'lahaa w^e find 
the same species represented by distinct varieties. Two of the Eaiatea species {P. 
targlda and P. attenaata), though having an extensive range, do not vary in a single 
feature ; the former, like P. clara and annectens, seems to be dying out. Three s])ecies 
(P. calli/era, citrina and aariculata) are restricted to single valleys, and the two former, 
like iurgida and attenaata, are very uniform in color and shape. All the other sjiecies, 
though having special headquarters, ha\e a greater or less range over two or more 
v alleys, and ten species have produced local varieties. 
Passing over the narrow lagoon to Tahaa, the latter about the size ot Huaheim* 
Ave find four endemic species, and, as before stated, tAVO local A'arietics of P. faha ; one 
JOUR. A. N. S. PHILA., VOL. IX. 
