118 VARIATION, DISTRIBUTION, AND EVOLUTION OF THE GENUS PARTULA. 
yellowish-red, reddish-brown, and brown individuals. Strigations of dark brown 
upon the general ground-color also occur. Color characters, like the direction of 
coil, may also be different in parent and offspring. A pillar tooth usually occurs, 
although it varies greatly and is sometimes entirely absent. ‘The other varieties of 
P. otaheitana display some but not all of the alternative or contrasted characters 
in the above categories; hence each one can be referred back to the Fautaua colony 
as the generalized starting-point. 
B. To the eastward of Fautaua, the valleys for several miles are inhabited by 
P. otaheitana amabilis Pfeiffer, the closest relative of P. otaheitana otaheitana. This 
variety rapidly loses its dextral components in passing to Hamuta and Pirai, 
beyond which such individuals occur only sporadically, if at all, as far as I have 
observed. The color-characters are essentially the same as in the Fautaua colony, 
but form and size change from valley to valley. Banded examples appear very infre- 
quently, and they are unlike the striped shells of other localities; it is amazing that 
heavily-banded examples of the variety named sinzstrorsa, to be described below, 
are confounded with amabilis in nearly all of the museum collections of the world. 
C. Beyond the territory occupied by amabilis, which in my experience ends 
with Ururoa Valley, begins the extensive area occupied by two sharply contrasted 
types. The first of these is P. otaheitana rubescens Reeve, a beautiful form which 
reaches its fullest and finest development in the far-distant valley of Oopu, at the 
extreme southeastern end of Tahiti nui and almost exactly opposite to Fautaua. 
This is the only primary variety that is always sinistral. It is large, yellowish or 
reddish in color, and devoid of strigations and revolving bands. All of its dis- 
tinctive characters are exhibited by the basic variety of Fautaua Valley, but in 
rubescens they exist without an admixture of others. In range, P. 0. rubescens 
extends around Tahiti nui to Apirimaue, and along the northern side of Taiarapu as 
far as Aiurua Valley. 
D. Partula otaheitana affinis Pease is the second primary variety whose range 
begins with Tuauru Valley, just beyond the region inhabited by P. 0. amabilis. It 
is relatively small, predominantly dextral, brown, and strigated; these are just the 
characters which P. 0. rubescens lacks. It exceeds the latter in abundance and in its 
territory of occupation, for it exists throughout the entire series of valleys of the 
eastern sector in greater numbers, as well as in nearly all of the valleys of Taiarapu. 
The range terminates with Apirimaue Valley, where P. 0. rubescens also stops. 
Well-marked subordinate varieties are to be found in certain valleys, and some of 
these have been earlier described as distinct species, ¢. g., dubia. Banded and plain 
examples occur in varying proportions in different stations, and sometimes sinistral 
mutants are found, almost always in widely-separated localities. 
E, F, G. The southern and western parts of Tahiti nui and Tairapu are inhab- 
ited by a complex series whose components agree so much inter se as to be set apart 
collectively from the other recognizable divisions of the species; nevertheless, 
differentiation within this series has resulted in the production of three distin- 
guishable varieties, to which specific names have earlier been given by Pease; 
they are sinistrorsa, sinistralis, and crassa, each of which occupies a definite territory 
