70 VARIATION, DISTRIBUTION, AND EVOLUTION OF THE GENUS PARTULA. 
snail, but it is recognizably different from the light tinge of a shell belonging to the 
contrasted class. 
Vathiria Valley.—In this area, clara is astonishingly abundant, especially in 
the lower part of the valley, where it occurs upon the vanilla vines as well as upon 
the trees and shrubs that usually harbor it. The greater abundance of snails belong- 
ing to all three primary color classes makes it possible to obtain more extensive data 
bearing upon the heredity of such color characters and also to obtain more accurate 
determinations of structural similarities and differences. Of the 92 adults secured, 
44 are light (fig. 17, plate 21), 18 belong to the darker class (figs. 18 and 23, plate 21), 
while 30 are banded (figs. 19 to 22, plate 21). The last-named are almost all marked 
with a broad brown girdle consisting of the major band fused across with the inter- 
mediate band between it and the sutural marking, as will appear from a comparison 
of the Vaihiria shells with those from Opiriroa. A few show only slight suffusion 
of this zone (fig. 19, plate 21), thus forming intermediates connecting the Teohu, 
Opiriroa, and Tiamao varieties with the typical Vaihiria shells, and with those from 
Faarahi. Among the lighter individuals, 14 bore 19 young assignable to the same 
color class. Only 4 with dark shells contained advanced young, all 8 of which were 
of the darker group. 16 banded snails furnished 20 young, with a distinct but 
narrow band in the position of the so-called major stripe of the adult. Turning to 
the measurements of the shells (table 25), it is plain that the three color-types are 
statistically distinct in some respects. It would seem that the banded class is more 
like the light division of unmarked forms, and this is further indicated by the fact 
that the embryonic shells of the banded snails usually have a light ground-color. 
Partula clara marmorata var. nov.—Ma ara to Farapa Valleys. 
Beyond the ridge that forms the eastern boundary of Vaihiria Valley, the shells 
of clara differ in certain characters from all varieties previously described. Their 
coloration is their most distinctive peculiarity. The ground-color is light, and upon 
this there are usually few or many transverse brownish markings that are not sharply 
defined, like the streaks present in the varieties already considered, and hence the 
shells present a somewhat marbled appearance; this variety is named marmorata 
(figs. 24 to 29, plate 21, and table 26). In addition, the whole shell is thick and 
chalky in texture, and the mantle-walls are often impregnated or incrusted with 
calcareous matter; the last character is not duplicated in any other primary variety. 
No banded examples were found in any part of the wide territory inhabited by 
marmorata. 
The valleys adjacent to Vaihiria on the east—namely, Maara and Tenaire— 
are within the area specified by Garrett as the territory occupied by c/ara in his time. 
Both in the chart and in the verbal description given by that writer this species is 
represented as entirely absent from Taiarapu and from the eastern quadrant. At 
present, however, this particular variety of marmorata is found, though sparingly 
as a rule, in valleys on all four sides of the peninsula, and up on the eastern side 
of Tahiti nui as far as Faarumai; only one valley beyond, viz, Papenoo, is 
