PARTULA OTAHEITANA. 293 
embryonic generation is less than among the adults. A secular change in the 
association of the higher ground may be indicated, or the figures may be too few to 
afford a sure basis for judgment. In either case the data have a certain positive 
value, especially for a future investigation of this area. The point of greatest 
significance is that the sinistral snails are genetically connected with the directly 
coiled group, which is a conclusion already drawn from the general similarity of the 
two groups in statistical determinations. 
TaBLe 248.—Partula otaheitana lignaria, Tipaerui Valley. Series of 1909. Full data of heredity. 
Young, dextral. Young, sinistral. 
Total. 
Plain. | Banded. Plain. Banded. 
Adults, dextral, plain........ 88 7 1 Reve 96 
banded...... 3 9 ma ays 12 
sinistral, plain........ 7 3 10 
banded...... 3 2 5 
MOtal sa cvistaw qeeraee) Mere 98 16 7 2 123 
(2) In investigating the heredity of the color-pattern, as unbanded or banded, 
some confusion might arise from the faintness of the bands in embryonic individuals, 
leading to their assignment to the wrong category of plain shells. Consequently, 
great care was taken to assure the correctness of the observations in all cases. The 
assembled data (table 249) give a remarkably consistent result, in that the total 
numbers of the two classes among the embryonic series agree closely with the 
figures for the corresponding classes among the parents. Each kind of the latter 
group contributes enough offspring to the contrasted class to bring the totals very 
near together. 
TaBLe 249.—Partula otaheitana lignaria, Tipaerui Valley. All years combined. 
Heredity of plain and banded color-patterns. 
Young, Young, 
plainwel|ibandedal|in core: 
Adults, plain. ........ 233 41 274 
banded....... 35 68 103 
Totaly ai wnvesreisttece 268 109 377 
(3) When we deal with the heredity of those differences in the depth of the 
ground-color that differentiate the members of both plain and banded groups, other 
sources of error enter into the problem. A shell destined to be “dark” in the adult 
condition is so thin and translucent in the young stages that it might appear to 
belong to the “medium” group. Again, a young shell might actually be “light” 
and become darker-colored only later in life. As it is impossible to exclude the 
errors arising from these sources, we can not regard the observed data as more than 
approximations to the real facts. As given in table 247 for the series of 1906 and 
1907, the discrepancies between the figures for the three kinds of shells among the 
parents and offspring indicate the effects of the errors specified above, if we assume 
a normal course of heredity for the character under consideration. If the contrary 
