46 
VARIATION, DISTRIBUTION, AND EVOLUTION OF THE GENUS PARTULA. 
entire island population, and it also was certainly an adult, as the animal contained 
eggs and embryos. 
slender, figure 4, is from Tipaerul. 
Tas_e 13.—Partula hyalina. 
Region. 
Tahiti. 
The longest shell, figure 3, is from Paraura Valley. The most 
Figures 5 and 6 showthe average shell as regards 
the proportionate measures; they are from Fautaua Valley. The shells of a thinner 
texture are illustrated by an example from Haavini Valley, shown in figure 7. 
Quite infrequently abnormal individuals are found where an injury has been repaired, 
as in a shell from Papenoo Valley, figure 8. 
ture is illustrated in figure 9. Finally, an adolescent individual devoid of the last 
whorl and flaring lip is shown in figure Io. 
Length. 
Shell. 
Width. 
Proportions. 
MEAN VALUE. 
The obliquity of the plane of the aper- 
Length. 
Aperture. 
Width. 
Proportions. 
Detailed statistical analysis of shells of major regions. 
Length aper- 
ture + length 
shell, pro- 
portions. 
Quadrant: 
North..... 
Tahiti nui... 
Taiarapu.... 
Whole island. | 
mm. 
15.2173 +.0340 
15.0850 + .0612 
15.4382 + .0776 
15.3806= .0785 
mm. 
8.7734 .0198 
8.6367 + .0400) 
8.7235 + .0348 
8.6388 + .0388 
p. ct. 
57.5707 = .0872 
57.2167 + .2050 
56.5000 = .1852 
56.1122+ .1774 
——: 
mm. 
8.8566 + .0223 
8.7200 + .0490 
8.9647 + .0372 
8.9265 = .0369 
mm. 
6.4783 + .0183 
6.5600 + .0368 
6.5255 + .0372 
6.4122 + .0306 
15.2452 + .0267 
15.5742 + .0503 
15.3098 + .0245 
8.8011 + .0256 
8.7415 + .0130 
8.7269 = .0149 
57.1747 + .0716 
56.4011 + .1447 
57.0227 + .0650 
8.8586 + .0168 
9.0813 + .0306 
8.9024 + .0150 
6.4860 .0138 
6.5714 .0243 
6.5028+.0121 
p. ct. 
73.1179+ .0998 
74.7667 = .1921 
72.8529 = .2472 
71.7245 + .1287 
73.1639 + .0836 
72.0824 .1207 
72.9514 .0723 
Dp. ct. 
58.1321 + .0877 
57.7166+.1706 
57.9117 .1901 
57.9286 = .1497 
58.0081 + .0661 
58.1593 .1077 
58.0378 + .0518 
STANDARD DEVIATION. 
Quadrant: 
Tahiti nui... 
Taiarapu.... 
Whole island. 
0.7349 + .0241/ 
7023 + .0433/ 
8216 + .0549 
8136+ .0555 
0.4276 .0140 
4597 = .0283 
-3686 + .0246 
-4024+ .0274 
1.8833 + .0618) 
2.3529 + .1449 
1.9603 + .1309 
1.8385 + .1254 
0.4823 + .0158 
-5623 + .0346 
-3934 + .0263 
-3826 + .0260 
-7633 + .0188 
-7098 = .0355 
.7802+ .0171 
4264+ .0105 
-3623+ .0181 
2.0462 + .0505 
2.0437 + .1022 
4789 = .0118 
4317+ .0216 
0.3949 + .0129 
-4223 + .0260 
-3939 + .0263 
-3166+ .0216 
2.1566 .0707 
2.2050 .1358 
2.6183 + .1749 
1.8872 = .1287 
1.8949 = .0621 
1.9586 .1206 
2.0114 .1344 
1.5518+.1058 
.3931 = .0097 
.3426+ .0171 
-4156+.0091 
2.0687 = .0453 
4782+ .0105 
-3852 + .0084 
2.3900 + .0590 
1.7043 = .0852 
2.3034 .0504 
1.6493 = .0361 
1.8885 + .0466 
1.5207 + .0760 
The next task is to compare the snails of different sections of the whole island. 
It appears from the figures of table 13 that the shells from Tahiti nui, as compared 
with those of Taiarapu, are shorter, narrower, and stouter; their apertures are also 
shorter, narrower, and more broadly oval; finally, the aperture is somewhat shorter 
with reference to the total shell length. Thus there are distinct morphological 
differences between the shells of the two main divisions of Tahiti as a whole. 
Furthermore, the shells of different quadrants possess diverse characteristics. 
For example, those of the headquarters region in the north are somewhat shorter 
than the southern shells, and far shorter than those of Taiarapu. 
They are also 
broader than the southern forms, and only slightly narrower than the individuals 
from Taiarapu. 
than the southern and peninsula classes. 
Finally, we may compare certain colonies which comprise enough individuals 
to render the statistical constants of their tabulated characters significant to some 
In proportionate measures, however, these shells are much stouter 
