208 VARIATION, DISTRIBUTION, AND EVOLUTION OF THE GENUS PARTULA. 
nant series is proven in this case by the return of the former’s recorded young to 
what must be regarded as the ancestral form of coil; indirectly it would appear that 
the three adult and single adolescent of the minority type were the products of 
sporadic mutation on the part of dextral parents. 
TaBLe 149.—Partula otaheitana affinis. Haavini Valley. Fecundity. 
_| No. of | Percent] No. of | No. of Total Average Average 
5 Records. : : % 
Series. gravid. | gravid. eggs. young. | contents. | for gravid. for all. 
Dextralenmnnrer 54 53 98.1 84 38 122 2.30 2.26 
Sinistralaeeeeeenee 3 2 66.6 1 3 4 2.00 1.33 
THE GENERAL TAIARAPU SERIES—TAUTIRA TO HAOMA VALLEYS. 
In the remaining ten valleys of the peninsula where collections were made, 
affinis was found in varying absolute and relative numbers, excepting in Aiavaro; 
rubescens 1s an associate in the valleys as far as Aiurua, while sznzstrorsa occupies the 
valleys of the southern tier from Vaiaaia to Vaipoe; hence in Vaiau, Hototunu, and 
Haoma affints is the only variety of P. otaheitana so far as the collections indicate 
the facts. Plain sinistral examples appear in Vaiau and Vaiaaia. In six valleys 
banded individuals occur that are of the zonata pattern almost without exception. 
The above general statements deserve considerable emphasis; it is by no means 
unimportant for the solution of our major problems that in Taiarapu there are three 
regions, the first (Tehoro to Aiurua) inhabited by affinis and rubescens, the second 
(Vaiau to Hototunu) inhabited by affinzs alone, and the third (Vaiaaia to Haoma) 
inhabited by affinis and sinistrorsa. If the “environment”’ were primarily respon- 
sible for the production of rubescens in the northern valleys of Taiarapu, and of 
sinistrorsa in the southern tier of the peninsula, it would certainly be anomalous 
for affinis to exist, as it does, in all parts of that minor portion of Tahiti. 
TauTIRA VALLEY. 
In this large area (which is the ancient crater valley of Taiarapu, like Papenoo in 
Tahiti nui) afinis is well represented, 207 adults having been taken. All but 2 
are plain with various shades of brown in color, except one shell with a red tone like 
the Tehoro specimen of plate 29, figure 56; this simulates the red type of sinistral 
rubescens found here and elsewhere. Two extreme variants in respect to shape and 
size are illustrated (plate 29, figs. 62 and 63). One of the two banded shells is so 
decorticated as to have lost the details of its pattern; the other (plate 29, fig. 64) 
has the wide basal band of zonata, but the median stripe is faint, except along its 
lower (left) border, so that it seems to be like dubia in the middle of the whorl. 
The statistical data (table 150) bring out the essential agreement of the light, 
medium, and dark divisions of the plain class, allowing for the high probable errors 
involved. Owing to the exigencies of travel at the time, and a night’s camp on an 
islet of the coral-reef, no fresh water was procurable for the expansion of the snails; 
consequently there are no data on fecundity and heredity. 
