PARTULA OTAHEITANA. 287 
one to three transverse reddish chestnut bands. ‘The lip is always white, and the parietal 
tooth is very seldom absent. ‘The inosculation with ofaheitana is so complete that it can 
not be even separated as a well-marked variety.” 
Hartman always united /ignaria with affinis; their alliance is real only so far 
as both primary varieties are referable to a parent otaheitana stock like that now 
existing in Fautaua Valley. Garrett is nearer the truth. 
In 1898 Mayer collected 115 individuals of /ignaria—all of which were dextral— 
together with 9 examples of P. hyalina. He pointed out the resemblance between 
banded /ignaria shells and striped individuals taken in Pirai and Hamuta Valleys 
and seemed to regard such forms as identical. In describing the latter we have 
already given the reasons for considering them as full members of P. otaheitana 
amabilis associations, and not as close relatives of banded types found elsewhere; 
now, on the basis of the following study of /ignaria, we will find further reasons for 
viewing the /ignaria and amabilis shells with stripes as independent of one another. 
Before proceeding to the analysis of the /ignaria association, it is necessary to 
describe certain topographical details of Tipaerui Valley. Its mouth is about 2 
statute miles west of Fautaua, as Garrett rightly states. At first it is about 0.375 
of a mile in width, but as one follows its course inland its sides converge and rise to 
greater heights. About a mile from the coast, it is only a few score yards in width, 
but above this point it opens out again. Not until nearly 2 miles up is the thick 
undergrowth of succulent plants encountered. At about 3 miles inland, one reaches 
the junction of two steams, one of which comes from an easterly source on the 
western side of the main divide between the upper parts of Fautaua and Tipaerul. 
The other stream arises on the steep slopes of Mamanu Mountain, a high peak on 
the ridge between upper Tipaerui and Taapuna Valley. But in both cases the 
mountain boundaries of Tipaerui in the interior are almost sheer precipices, prob- 
ably 1,500 or more feet in height, whose altitude is such that snails do not climb to 
their summits; hence they constitute virtually impassable barriers to migration, 
although the horizontal distances from Tipaerui to Fautaua and Taapuna Valleys 
are very short. 
In 1906, during the wet season (February and March), collections were secured 
from the lower part of the valley along the sides of the single main stream; a point 
about 2 miles from the coast, at a barometric level of 750 feet, marked the limit. 
In 1907, during the dry season, an additional series was collected from this area, 
somewhat more inland, for the purpose of securing comparative statistics on fecun- 
dity. Again in 1909, at the same time of the year, a more thorough exploration was 
made, this time in the further interior, along the east and west forks to very nearly 
the limit of habitation. The branch streams unite at a barometric level of almost 
800 feet; above 1,000 feet the snails are very scarce. The collections, therefore, 
represent the inhabitants of different sections of the whole valley, as follows: 1906 
lower area, 1907 middle area, 1909 upper area, with (a) east fork and (b) west fork 
distinguished. Although the snails of these areas are close relatives, to be united 
under the designation /ignaria, interesting differences come to light when the three 
collections are analyzed and compared in detail. 
