PARTULA OTAHEITANA. 245 
The gravid parents are represented numerically in the three classes, thus: 
- Plain and 
ta banded eae Total. 
young. 
Whole series: 
Rainer 41 1 3 45 
iBandedmerasiias 11 2 49 62 
Sinistral series: 
Plainterereraerier 26 0 3 29 
iBandedtrersnier 8 1 31 40 
Dextral series: 
iMbiinoapanonds 15 1 0 16 
iBanded@enrrce 3 1 18 22 
Considering first the whole series, the departure of the empirical figure from 
expectation amounts to 26.6 per cent, under the assumption that banding is a Men- 
delian recessive, while the corresponding difference is 30.6 per cent under the con- 
trary hypothesis. 
In the analysis of the sinistral series alone, the differences are 34.4 and 27.5 
per cent, respectively; in the case of the dextral series the difference under the first 
assumption is 31.2 per cent, but the contrary hypothesis leads to an abrupt halt, 
in so far as no double dominants would be indicated as existing. Here again, then, 
the facts tend to prove the same two points as in the case of the Tenaire analysis. 
Faaraut VALLEY. 
Only phea and cestata are represented in this population, which is sinistral in a 
series of 465 adults, although one dextral individual of each class also was found; 
naturally these last can be disregarded. Plain shells amounted to 65 per cent, and 
banded to 35 per cent. The classified parents are as follows: 
Plain adults: plain young, 138; both kinds, 9; banded young, 18=165 
Banded adults: plain young, 25; both kinds, 5; banded young, 48=78 
Taking the banded pattern as recessive, the proportion of DD, DR, and RR 
mates of the snails exhibiting that character are 14:37:27, after an adjustment to 
the extent of % of the number in the first and third classes; the figures are not 
improbable. Carrying out the analysis of the plain parents, expectation gives 
66:99, and corrected observation gives 78 : 87, for the class with plain young only 
and the class with both kinds. The difference amounts to 7 or 7.27 per cent. 
On the supposition that banding is dominant, the figures for the three genetic 
classes are I5 :33:107, which are obviously unnatural, and the difference in the 
independent test amounts to 23 in 78, or 29.5 per cent. ‘The findings are in clearer 
accord with the former assumption, and with Mendelism as a working hypothesis. 
Moaroa VALLEY. 
Again the material is simple, as all of the snails are sinistral, and apex is absent. 
Plain shells amount to 61 per cent and the banded to 39 per cent of the adult popu- 
lation, comprising 434 individuals. The classified parents are as follows: 
Plain adults: plain young, 47; both kinds, 0; banded young, 9 =56 
Banded adults: plain young, 13; both kinds, 0; banded young, 20=33 
