TERRESTRIAL MOLLUSCA INHABITING SOCIETY ISLANDS. 45 
inhabited by four species found nowhere else. One (P. teeniata), which has its 
metropolis in a large valley on the north coast, is, like P. Otaheitana, a very variable 
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. lineata, which 
inhabits that part of the island not occupied by feeniata, is nearly as variable as that 
species. P. elongata, which is confined to the same portion of the island as /ineata, 
is less variable, and where it comes in contact with teeniata we find hybrids between 
the two so common as to suggest a certain degree of fertility in the intermediate forms. 
P. Mooreana, 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 islands in the group. 
Huaheine, like Moorea, possesses four endemic species, all of a different type from 
those inhabiting the preceding two islands. Two (P. arguta and cannectens) 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 inhabited by 
twenty species of Partu/a, being one-half of the number assigned to the whole group, 
and eightcen are found nowhere else. ‘These, according to Dr. Hartman’s divisions, 
include not only the type, but five out of his fifteen subgenera, two of 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 been regarded as distinct species. Six species are strictly terrestrial. 
The tine large typical P. fabu, which has its metropolis at Utuloa on the north end of 
the island, has spread into nearly all of the valleys, and is equally as variable in all 
parts of the island as in its headquarters. On the adjacent island of Tahaa we find 
the same species represented by distinct varieties. ‘Two of the Raiatea species (P. 
turgida and P. attenuata), 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 species 
(P. callifera, citrina and auriculata) ave restricted to single valleys, and the two former, 
like turgida and «attenuata, are very uniform in color and shape. All the other species. 
though having special headquarters, have a greater or less range over two or more 
valleys, and ten species have produced local varieties. 
Passing over the narrow lagoon to Tahaa, the latter about the size of Huaheine 
we find four endemic species, and, as before stated, two local varieties of P?. faba ; one 
if JOUR. A. N. S. PHILA., VOL. IX. 
