190 VARIATION, DISTRIBUTION, AND EVOLUTION OF THE GENUS PARTULA. 
might seem that these three shells represent stragglers from the Ururoa amabilis 
colony, but their individual measurements are well within the ranges of the char- 
acters displayed by the dextral series, in the several instances, while the relation- 
ship thus indicated is finally established by the fact that two young, borne by one 
of them, are dextral and light-brown in color; the Ururoa snails breed true to their 
sinistrality. Hence these snails are to be regarded as sporadic mutants from the 
general stock. 
TasLe 120.—Partula otaheitana affinis. Tuauru Valley. 
MEAN VALUE. 
Shell. Aperture. Length aper- 
ture + length 
Series. No. shelitpropors Tooth, index. 
Length. Width. Proportions. Length. Width. Proportions. tions. 
mm. mm. p. ct. mm. mm. p. ct. p. ct. 
Plain, light.) 78) 17.4000+.0660) 10.3795 .0311| 59.6538 .1604) 9.3538 .0355| 7.3384 .0249| 78.4487 = .2135| 53.7692+.1392| 3.1410+.0661 
dark.| 184| 17.3946 .0399| 10.2945 + .0224) 59.0978+ .0997| 9.3119+.0245| 7.2848+.0180) 78.2653+.1320] 53.3641+.0950} 2.7884 + .0302 
Plain, all. .| 262) 17.3962 .0336| 10.3198+.0183) 59.2633 + .0854| 9.3252+.0202) 7.3008+.0148) 78.3206+.1125| 53.4847 .0790| 2.8914 .0294 
Banded...| 92) 17.3391=+.0507| 10.3326+.0276| 59.4891=+.1611) 9.2978+.0302) 7.3326+.0224) 78.5761+.1636| 53.5217+.1269| 2.7912+.0420 
Nilo 500006 354) 17.3814 .0282| 10.3232+.0153) 59.3220+.0759| 9.3181 .0169) 7.3091 + .0125) 78.3870+ .0936] 53.4944 .0671] 2.8650 .0249 
Sin., plain.. 3) 17.3500 .2754| 10.5666 .1468) 60.8333 +.1836| 9.6333+.0734| 7.6333 .0368) 79.5000+.5507| 55.1666+.4856] 3.0000+.0 
5 
STANDARD DEVIATION. 
Plain, light.| 78] 0.8639+.0466) 0.4080+.0220} 2.1005+.1134) 0.4654 .0251| 0.3267+.0174) 2.7960+.1509| 1.8234 .0984| 0.8656 .0467 
dark.| 184 -7818+ .0282 4583+ .0158} 2.0057+.0705| .4922+.0173) .3674+.0127) 2.6548+.0933| 1.9133+.0671| .6152=.0213 
Plain, all. .| 262 -8069 + .0237 .4399 = .0128) 2.0502+.0603} .4847+.0143) .3566+.0104| 2.6990+.0795] 1.8961=.0558] .7133+.0208 
Banded...| 92 -7210+ .0358 -3926=+ .0195} 2.2912+.1139) .4298+.0213) .3193+.0159) 2.3274+.1156| 1.8057+=.0857| .6108+.0297 
INE aes 354, .7860.0199| .4281-.0108] 2.1178+.0537| .4712+.0120| .3475+.0088 2.6100+.0662| 1.8730-.0474| .7029+.0176 
Sin., plain.. 3 -7071+.1947 .3771= .1038 4714+ .1298] .1886+.0519]} .0946+.0260| 1.4142+.3894) 1.2470+.3434| .0 
The statistics of fecundity (table 121) show an average productivity for the 
season of collection. The data of heredity (table 122) for the dextral snails prove 
that the several subdivisions breed their own respective kinds in the majority of 
cases, but also produce young of the other classes. The summary gives almost 
exactly the same proportionate numbers in the color-classes of the young and of 
the gravid adults, which is a remarkable and unusual agreement. 
Of the three sinistral adults, one was barren, another contained a single egg, 
and the third (as noted above) bore two light-brown, plain, and dextral young. 
Obviously the reversed individuals are genetically related to the prevalent stock. 
AHonu VALLEY. 
The collection of affinis from Ahonu comprised fewer numbers than that just 
described, but still enough to provide definite statistics for inter-valley comparisons, 
while its intrinsic composition is interesting on its own account. It is noteworthy 
that rubescens exists in large relative numbers in this area, whereas very few were 
found in Tuauru. Only 3 out of 149 adults were dextral and banded, while an equal 
number were sinistral and plain, thus giving a composition that is markedly different 
from that of the earlier-described colony. Like the majority of the banded speci- 
