136 VARIATION, DISTRIBUTION, AND EVOLUTION OF THE GENUS PARTULA. 
to be different from the general average, and their variability would be unusually 
high. Such are the facts. 
The color-classes of the plain shells differ among themselves and in various 
ways in the several characters. There is no simple generalization that can be 
formulated. 
The statistics relating to the tooth (table 70) show no very significant differ- 
ences between comparable classes. 
Tasie 70.—Partula otaheitana amabilis, Hamuta Valley. Statistics of tooth-development. 
Distribution. Constants. 
No. 
None.| Trace.} Tooth. | Large.| Very large. Mean Standard 
(1) (2) (3) (4) (5) : deviation. 
Sinistralaplainjaee levee eras 33 1 2 20 10 0 3.1818 .0789 0.6721 .0558 
AN Were eericecis 52 2 2 31 17 0 3.2115=+ .0664 -6888= .0469 
100 basa rencnrol 172 9 12 109 41 1 3.0755 .0376 .7314 .0266 
Wife toretvers 36 0 6 24 6 0 3.0000 = .0649 .5773 .0459 
Sinistral, banded........... 6 1 1 4 0 0 2.5000 .2102 . 7637 .1486 
Sinistraleplainwall sees 293 12 22 184 74 1 3.1024 .0277 . 7033 .0196 
Sinistral alleen 299 13 23 188 74 1 3.0903 + .0276 .7096= .0195 
Mextral plain wel rier 35 1 4 19 11 0 3.1428 .0801 . 7027+ .0566 
MD 5 vapave-dveveiceys 27 3 3 15 6 0 2.8889 .1135 .8749= .0802 
Wi circra sever ays 92 4 11 57 20 0 3.0109 .0502 . 7146 .0355 
IVs sroye deere yore: 19 1 2 14 1 0 2.8947 + .1247 .6403 = .0882 
Dextralsibandedemerererereiee 2 1 1 0 0 2.5000+ .2384 . 5000+ . 1686 
Dextral, plain, all.......... 173 9 20 105 39 0 3.0058=+ .0380 .7410= .0269 
Dextral jall\ cycles. eenevesstrocks 175 9 21 106 39 0 3.0000 .0377 .7407= .0266 
HEREDITY. 
As in the case of the generalized stock of Fautaua Valley, in Hamuta there are 
snails of each coil which produce young of the opposite nature (table 71). The 
total percentage of sinistral young is so slightly in excess of the figures for the adults 
that no significance attaches to the difference. 
The inheritance of the fundamental ground-color, on the basis of the data in 
hand, is by no means so close as one might expect. Too much weight should not 
be laid upon the figures in question, on account of the difficulty in deciding upon 
the exact class to which an embryonic snail should be assigned, for such snails do 
not establish their definitive colors as early as they do in the Fautaua colony. In 
addition, the deeply-tinged apex is exhibited by a large proportion of the shells of 
the lighter color-classes, and as the tinged apex appears in the very young condition 
there is some tendency to refer such individuals to a darker color-class—obviously 
an erroneous assignment. It is not so much an error in observation as a difficulty 
in the material that accounts for the lack of stricter heredity in the statistics as 
tabulated. 
The banded character is exhibited by 1 out of 6 produced by adults of this 
kind. The indicated absence of banded sports among the young of plain parents 
may be accounted for by the translucence of the embryonic shell. 
