162 VARIATION, DISTRIBUTION, AND EVOLUTION OF THE GENUS PARTULA. 
as in this section, or it is very slight if it occurs at all; apparently, then, it is 
manifested on account of a defect in the constructive tissues in certain individuals, 
and is not to be interpreted as an environmental effect per se. 
A unique parti-colored form occurs in this valley in small numbers, where the 
basal half of the main whorl lacks the clear red of the rest (plate 27, figs. 32, 33, 36, 37). 
The colony as a whole comprises large and vigorous snails (table 103), but one 
extraordinarily small reddish mutant occurs (plate 27, fig. 31). It is scarcely larger 
than specimens of the dextral afinis which live here, but it is a complete miniature 
of the true rubescens in all respects of color, coil, surface, and form. 
When the three color types are compared on the basis of statistical characters 
(table 103), they exhibit certain differences, some of which are significant. ‘This is 
especially true of the red shells as contrasted with the clear yellow group, for the 
former are distinctly narrower absolutely and more slender proportionally, both 
in the case of the whole shell and in that of the aperture. The “white” and clear 
“yellow” classes do not differ markedly. 
TasBLe 103.—Partula otaheitana rubescens, Papeiha Valley. Comparison of color-classes. 
MEan VALUE. 
Aperture. Length aper- 
- ture + length q 1 
Series. shell) propor® Tooth, index. 
Length. Width. Proportions. Length. Width. Proportions. tions. 
mm. mm. p. ct. mm. mm. Pp: Ct. p. ct. 
White. 19.8000 + .1386) 11.2400 .0954) 56.3000 .3276) 10.1000 .0972) 7.7400 .0655| 76.9000 .4069| 51.0000 .3472} 1.1000 .2122 
Yellow 20.1025 + .0753) 11.3689 .0357) 56.3525 .1939| 10.2246=+ .0388) 7.8836 .0257| 77.1393 .2298| 50.8279=.1396| 1.0000+ 0 
Red.. 20.2625 = .1330} 11.1700+.0664| 55.3500 .2585) 10.1600+.0629| 7.7450 .0536) 76.3000 .3102} 50.1250+.1779| 1.0000= 0 
All 20.1320+ .0633) 11.2856 .0327| 56.1829+.1501| 10.1901 = .0325) 7.8207 .0262| 76.8153+.1744] 50.5901+.1072) 1.0089 .0060 
STANDARD DEVIATION. 
White 10} 0.6500=.0980} 0.4476=.0674) 1.5362=+.2316) 0.4560+.0687) 0.3072+.0463) 1.9078+.2877| 1.6278+.2448) 0.9950+.1500 
Yellow 61 -8719 = .0532 4143+ .0252) 2.2458+.1371 4496+ .0274, .2986+.0182| 2.6614+.1625| 1.6167+.0987| 0 
Red. 40| 1.2474+.0940 -6222+ .0469) 2.4243+.1828 -5902 == .0445) .5029+.0379| 2.9086+.2193) 1.6686+.1259| 0 
AMS 354 111 -9889 + .0448) -5106+.0231| 2.3439+.1061 .5075=.0230) .4100+.0185 1.6741 .0758| .0940+.0042 
1The numbers are respectively 10, 61, 41=112. 
The tooth is completely lacking in all of the shells, with the sole exception of 
one white example, which exhibits a faint trace of this structure. It may be noted 
here that the tooth never appears in shells from the valleys throughout the rest of 
the range of rubescens. 
In fecundity at the time of collection (table 104) the red-shelled snails were more 
active reproductively, but the percentage of young for each gravid adult does not 
exceed the figure for the yellow class or for the two lighter groups taken together. 
As regards the heredity of color-characters (table 104), it is clear that the 
“white” class is made up of snails from the yellow, or at least from another group, 
for not a single immature snail-shell was “white.”’ It is interesting ‘to note that all 
of the young from such adults were yellow, and never red. Contrasting the red 
snails with those of the other two classes taken together, it appears that the former 
