30 VARIATION, DISTRIBUTION, AND EVOLUTION OF THE GENUS PARTULA. 
While the full list of recorded Tahitian species numbers 8, the present study 
is concerned with 6, all of which provide most significant data for the problems of 
distribution and evolution, although no two of them agree in the details of their 
occurrence and variation. Partula hyalina Broderip is a small arboreal species 
with a white shell that exists all about the island without variations in color, 
although it is far from uniform in size and shape, as it has been supposed to be; the 
same species occurs in the Cook and Austral Islands. Partula clara Pease is also 
an arboreal species with a small shell that now ranges over about three-fourths of 
Tahiti, although it was formerly more restricted in its territory; it exhibits an 
interesting condition of differentiation into subordinate types that are well on their 
way toward the status of subspecies. In sharp contrast with these two, Partula 
jilosa Pfeiffer is confined to a single valley in the drier northern section of the island, 
although in this one area it varies greatly in size and color. Partula otaheitana 
arfinits 
Tubescens 
rubescens 
hyalina Via ¢ 3 
JS [Lowland : attenuata f 
‘ H hyalina 
, 
U 
i no 
i Forest | 
’ 
H / 
attenuata 
hyalina \ ¥,, istrorsa 
attints 
Text-Fic. 2.—Garrett’s chart of the distribution of Tahitian Partulz in his time, as published in Hartmann’s paper. 
Original form and lettering. 
Bruguiére forms the vast bulk of the whole population, existing in unusual numbers 
in every habitable valley of the island; it has differentiated into 8 subspecies of 
closer or wider affinities, and in its entirety it affords ideal material for the 
analysis of the problems under consideration. The sixth species, Partula producta 
Pease, differs from the foregoing in its terrestrial habit; it has been found in one 
valley only, and hence it adds little of interest for the problem of distribution. 
Like the last-named, Partula stolida is described by Garrett from Papenoo Valley 
only, where, however, I failed to discover it in spite of repeated efforts; some con- 
fusion exists in the identification of this form, which is referred to P. compressa by 
Pilsbry, although the true compressa is a variety of the Raiatean species P. radiata 
Pease, in the opinion of Garrett and myself. Finally, in Tahiti and also in Raiatea 
occurs the arboreal species Partula attenuata Pease, where it lives among the top- 
most branches of the trees; only two or three specimens were secured in Tahiti, 
