274 VARIATION, DISTRIBUTION, AND EVOLUTION OF THE GENUS PARTULA. 
The statistics of fecundity (table 229) are noteworthy because the rates are 
different in the two annual series, although they were taken at the same time of the 
year, and because the cestata differ in opposite ways from the phea class; the num- 
bers of the latter are too few, however, to be really significant. 
The young shells in all cases were sinistral and unbanded. 
PARTULA OTAHEITANA CRASSA OCCIDENTALIS SUBVAR. NOV.—AOUA AND PAPEHUE 
VALLEYS. 
The two valleys just to the north of Orofere, namely, Aoua and Papehue, are 
occupied by otaheitana associations which differ in certain striking ways from the 
crassa colonies previously described. Their color-composition is their most promi- 
nent distinctive feature; no banded or cestata individuals and very few brown phea 
confluens are to be found, while the bulk of the population in both cases is made up 
of red-shelled and yellow-shelled snails that resemble rubescens in colors as well as 
in their sinistral coil. On account of their geographical situation, the two colonies 
are treated under the quaternary term occidentalis. 
Although the topography of the western sector has been described earlier, both 
in the general section and also in connection with the colonial distribution of Partula 
clara and Partula nodosa, certain essential points demand specific mention again. 
The land-mass between Orofere and Punaruu is a compact triangular sector forming 
the coastward slopes of the mountain peaks of Mahutaa (4,943 feet) and Taiti 
(4,589 feet). The ravines and gullies north of Orofere grade regularly from Aoua, 
which is the longest and narrowest, to Papehue, Atehi, and Maruapoo—the last of 
which is the shortest and smallest of the series. We have learned how Partula 
nodosa and Partula clara are differentiated in the valleys of this sector; it is inter- 
esting to find that in the two habitable areas of Aoua and Papehue there is a clearly 
marked quaternary form of Partula otaheitana as well. 
The collections from Aoua were secured during two excursions in 1907, and 
comprise 650 adults, 116 adolescents, and 231 embryonic young obtained from the 
first-named. From Papehue 143 adults and 84 adolescents were taken in 1906 and 
in 1907; from the former only 12 embryonic records are at hand, because the full- 
grown snails were kept alive for study and transport to the home laboratory. The 
absolute and relative numbers of adults assigned to the three color-groups are as 
follows: 
Number. Per cent. 
Valley and year. 
Yellow. Red. Brown. | Yellow. Red. Brown. 
AOVE, MOO sosssdotne 304 341 5 46.8 S78 0.7 
Papehue, 1906....... 40 29 0 58.0 42.0 ots 
190 7B See: 38 35 1 Silos} 47.3 eS 
FN ito acd Od on 78 64 1 54.5 44.7 0.7 
The yellow class (plate 33, figs. 31 to 36, 46, and 47) comprises individuals that 
grade from whitish yellow to a rich yellow-orange, invariably lacking any tinge of 
red; the apex is often of a more intense hue, but it is never purple or red, as in some 
