198 VARIATION, DISTRIBUTION, AND EVOLUTION OF THE GENUS PARTULA. 
TasLe 132.—Partula otaheitana affinis erythrea. Farapa Valley. Heredity. 
Young, plain. Young, banded. 
All All 
plain. | banded. Total. 
Adults 
Plain 
Wii tishteeesee rere 13 8 1 
igh tech once ae 155 71 5 389 21 231 $410 
BLOW Eee 73 69 8 7 
Banded 
Red dish serene 15 aes 21 3 39 
Brown, distinct.... 5 4 1 11 40 56 | 21; 96 
suffused.... 8 8 sits 20 36 
Motalintever cere 269 160 36 41 429 77 506 
THE EASTERN SERIES OF AFFINIS—FAARUMAI TO FAONE VALLEYS. 
In the valleys of the eastern sector beyond Farapa, affinis exists in substantial 
numbers; the coil is dextral except in a few individuals from one valley only, and 
the unbanded form of coloration predominates to degrees that vary from 76 to 99 
per cent. The red over-tinge, which is a colonial character of the single Farapa 
association, disappears almost entirely, being exhibited by infrequent individuals 
just as in Ahonu; the light red bands of so large a number of the erythrea shells 
never recur. 
Two types of shells with brown encircling bands occur in varying numbers in 
the eastern valleys and elsewhere to the southeast, excepting only in Tehoro and 
Haavini Valleys. In the one form the three bands are narrow and are sutural, 
median, and basal or umbilical in position; this is the dubia color-form now 
encountered for the first time as a distinct type, though certain of the Farapa shells 
anticipated it. Its status in the literature is somewhat peculiar. Pilsbry states 
(p. 189) “the var. dubia was not defined by Pease, but only mentioned as a form of 
varia, in P. Z. S. 1864, p. 675. Its first published definition was in Garrett’s note 
* * *” quoted herein on page 186. In his own volume on Partula, Pilsbry regards 
the distinctive coloration as a character of a primary varietal value, thus making 
dubia equivalent to rubescens, amabilis, etc., as well as to affints itself; as a matter 
of fact dubia is not independent of the last-named, but is merely a color-form of 
that primary division of Partula otaheitana, and is to be written dubia. The second 
color-form, called zonata, replaces the narrow bands by broad stripes; transitional 
forms between this and dubia are found in several valleys. 
If these two types occurred only in separate territories, and if each constituted 
a very large or preponderating section of the population in its valleys, then we would 
be justified in giving the terms the taxonomic value of secondary varietal distinc- 
tions, speaking of P. 0. affinis dubia and P. o. affinis zonata. As a matter of fact, 
the banded shells of either type never predominate, while furthermore their terri- 
tories are not distinct, like those of sznzstrorsa, sinistralis, and crassa of the southern 
regions of Tahiti. At times both color-forms exist in the same valley, while at 
others a colony comprising dubia is found to lie in the midst of series of valleys in 
which only zonata banded shells occur. It is possible that in the course of the future 
