258 
VARIATION, DISTRIBUTION, AND EVOLUTION OF THE GENUS PARTULA. 
number the plain ones; they fall into the three subordinate divisions distinguished 
and illustrated in the Opiriroa colony. The unbanded shells are dark, on the whole, 
segregating into phea solida of the original kind, and phza confluens (plate 32, figs. 32 to 
34); some of the latter approach but do not attain the striata form of coloration. 
Statistically (table 206) the shells of this colony prove to be larger and narrower 
than those of the eastward associations; solida and confluens differ little in length, 
but shells of the latter subclass are narrower and more slender than those of the 
In the comparison of the subordinate cestata groups, it appears that in 
all three proportionate measures the figure increases with the intensity of coloration; 
the differences, it is true, are not always statistically significant, but the changes 
are consistent nevertheless. 
former. 
Series. 
phza confluens. . 
solida.... 
phea 
No. 
Length. 
mm. 
18.4812 .0727 
18.5193 + .0722 
TaBLeE 206.—Partula otaheitana sinistralis. 
Shell. 
Width. 
mm. 
10.2125 .0399 
10.1323 += .0354 
Mean VALUE. 
Proportions. 
p. ct. 
55.1875 + .1876 
54.6452 + .1813 
9.4774 .0362 
Length. 
mm. 
9.4708 + .0363 
Aperture. 
Width. 
mm. 
7.2250 .0334 
7.1806 + .0308 
Otuna Valley. 
Proportions. 
p. ct. 
76.2708 = .2188 
75.6290 + .2189 
Length aper- 
ture + length 
shell, propor- 
tions. 
p. ct. 
51.1458 .1858 
51.1935 + .1302 
Tooth, index. 
2.8958 + .0848 
3.0161 + .0761 
18.8060+.1110 
18.4797 + .0579 
18.6320+ .0458 
10.3000 + .0539 
10.2604 .0256 
10.4540 + .0313 
54.7400 .3523 
55.4640 .1505) 
56.0500 = .1422) 
18.5027 + .0516 
18.5788 + .0357 
18.5546 + .0294 
9.6420 .0314 
9.6280 + .0544 
9.5450 = .0294 
7.2440 + .0497 
7.2477 = .0240 
7.3340 .0252 
75.4200 .4018 
75.9594 .1836 
76.0200 .1670 
51.0600 .1752 
51.4639 = .1242 
51.6000+ .1295 
2.8462 + .1082 
2.8919 = .0449 
2.9300 += .0470 
10.1673 + .0198 
10.3466+ .0192 
54.8818 + .1292 
55.6356 .1017 
9.4745 + .0258 
9.5949 + .0201 
7.2000 + .0227 
7.2839 .0165 
75.9090 = .1597 
75.9280 .1196 
51.1727 .1094 
51.4788 = .0825 
10.2896 .0159 
55.3960 = .0821 
9.5566 .0161 
7.2572 .0135 
75.9220 .0962 
51.3815 + .0664 
2.9637 + .0568 
2.9030 + .0313 
2.9222 + .0279 
pheea confluens. . 
solida .... 
(ne 
phaai twas 
STANDARD DEVIATION. 
48) 0.7472+.0514) 0.4101+.0282) 1.9274+.1326) 0.3731+.0257) 0.3431+.0236) 2.2476+.1547) 1.9093+.1314| 0.8718 .0599 
62} .8427+.0510) .4133+.0250) 2.1163+.1282) .4223+.0256) .3600+.0218) 2.5557+.1548) 1.5196+.0921) .8883+.0538 
25 .8232+.0785| .4000+.0381) 2.6119+.2491) .4035+.0385|) .3688+.0351) 2.9788 .2841) 1.2986+.1239| .8177+.0765 
111 -9046 + .0407 -3998+.0181) 2.3516+.1064| .4601+.0208) .3754+.0170) 2.8688+.1298) 1.9402+.0878] .7020+.0317 
100 .6799+ .0324, .4646+.0221) 2.1089+.1005| .4651+.0222) .3742+.0178) 2.4757=+.1181) 1.9209+.0916) .6965=+.0332 
110 -8026 = .0365 .3084+.0140) 2.0089+.0913) .4019+.0182) .3534+.0160) 2.4837+.1129| 1.7009+.0773| .8834+.0401 
236 -8148 = .0252 4381+ .0136 2.3194+.0719} .4593+.0142) .3767+.0117| 2.7275+.0846) 1.8809+.0583) .7138=.0221 
346} .8117+.0208) .4390+.0112) 2.2657+.0580) .4454+.0114) .3715+.0095) 2.6525+.0680) 1.8311+.0469, .7721+.0197 
As the time of collection fell within the wet season, the figures for fecundity 
(table 207) are unexpectedly high. The two color groups are almost exactly alike. 
The noteworthy feature as to heredity is the small number of banded young. 
The distinctive bands must make their appearance only after the birth of the young 
snails destined to be cestata as adults. 
In this connection it may be added that 
shells of subdivision (c) are relatively scarce among the adolescent population, as 
would be expected from the fact that their distinguishing characters appear only 
in the coloration of the body whorl. 
