292 VARIATION, DISTRIBUTION, AND EVOLUTION OF THE GENUS PARTULA. 
taken during the months with less rain, comprises a larger proportion of bearing 
members, but their productivity is scarcely greater than before. In 1909, the 
snails showed a good average breeding ability, both in the proportion of gravid 
individuals and in the higher fecundity of these. Taking all the data into account, 
it would seem that in Tipaerui, at the time of the wet season, the snails were near 
the close of a period marked by reproductive activity, when the number of eggs was 
small as compared with the number of young snails about to be born. Later in the 
year, renewed breeding activity is manifested by more individuals, when the eggs 
greatly outnumber the embryonic young. With the cessation of egg-production 
toward the month of January, the condition of the 1906 series would again supervene. 
HEREDITY. 
We come finally to the problems dealing with the genetic interrelationships 
(1) of the dextral and sinistral classes, (2) of the plain and banded groups treated 
generally, (3) of the light, medium, and dark subdivisions of the unbanded and 
banded classes. “To these we may add (4) the more difficult question as to the 
possible Mendelian course of inheritance in the case of the contrasted banded and 
bandless characters. 
TasLe 247.—Partula otaheitana lignaria, Tipaerui Valley. Series of 1906 and 1907. 
Furi Data or HeErepity. 
Young (all dex.), plain. Young (all dex.), banded. 
Total. 
Light. | Medium. | Dark. | Light. | Medium. | Dark. 
Adults (all dex.): 
Riainwlichtaemeeeeeecr 10 2 4 1 17 
MeECIU Meee 42 39 2 13 8 5.0 104 7168 
darks 2 he ors: 8 19 12 3 4 1 47 
Banded lich Caserversscier 3 2 ae 6 1 1 13 
medium:.....- 8 9 4 24 17 Ke 627 86 
darko. {akon 1 2 4 4 11 
Motal syne cc Gevsere 72 73 18 54 35 2 254 
SSS EEO EA OE SS SY 
163 91 
SUMMARY. GROUND-COLOR, COMBINED PLAIN AND BANDED. 
Young, Young, | Young, 
light. medium. | dark. 
Adults, light......... 23 
medium...... 87 
darkest 16 
Motal vce eee here: 126 
(1) All of the snails comprising the series of 1906 and 1907 were dextral; all 
of the 254 embryonic young dissected from such gravid adults were also dextral 
(table 247). Of the mixed upland collection of 1909, the dextral adults produced 
only 1 out of 108 reversed young (table 248), while the sinistral adults bore 7 dextral 
and 8 sinistral offspring; thus the total number of reversed individuals in the 
