PARTULA OTAHEITANA. 127 
The differences in the case of the three shell characters are significant with 
high probability; the divergence in width and proportions of the aperture are also 
probably significant, and the proportion of aperture length to shell length is also 
different with practical certainty; finally the tooth reaches a higher average degree 
of development. 
Yet the relationship of the banded to the plain shells is indubitable. The 
single young snail taken from a banded adult is plain (q. v.), and furthermore, in all 
cases the measurements of the banded shells fall well within the range of variability 
of the same character of the plain shells. Therefore, we can not regard as stragglers 
the striped individuals which have come from the neighboring valley of Hamuta or 
from any other place, where similarly colored shells may be found more frequently; 
it seems more justifiable to consider them as mutants produced only sporadically 
by the general unbanded stock. According to the latter interpretation it would 
naturally follow that the dimensions of such sports would follow those of their 
parents, and only if such parents occupied widely separated positions along the 
range of a given character, and if, furthermore, their mutant offspring were actually 
numerous, would the average value of this character be approximately the same in 
the small group of mutants as in the class of unbanded snails taken as a whole. 
The second general point established by the figures of table 61 is that the darkest 
sinistral snails tend to be smaller than their similarly coiled relatives, but they do 
not differ to a significant degree. Cross-breeding between and among the members 
of all four classes in each coil prevails to a great extent; wherefore no distinctive 
dimensional peculiarities of any color-class would be expected. 
FECUNDITY. 
The statistics of fecundity for the Fautaua colony are given in table 63. Here 
it is permissible to combine the data for the sinistral and dextral individuals. Con- 
ceivably the two kinds might differ in their rates of multiplication, and if so, the 
difference would be a potent factor of change in the colony as a whole as regards 
the proportionate numbers of the two kinds of shells; but the facts indicate that 
there is no real difference in the rate of reproduction. 
TaBLE 63.—Partula otaheitana otaheitana, Fautaua Valley. Statistics of fecundity. 
Average 
No. of | Per cent Total Average 
Group. Records. gravid.| gravid. Eggs. | Young. contents. for for all. 
gravid. 
Sinistral, 1906, Feb....:........ 185 91 49.19 62 96 158 1.73 0.85 
MOO, JUIN (O)scoccoos 169 138 81.66 195 143 338 2.45 2.00 
IGM, SAMFsco0oc0d0000 67 59 88.06 103 50 153 2.59 2.28 
Dextral, 1906, Feb............. 160 75 46.87 57 74. 131 1.74 0.82 
1907, June (?)......... 128 106 82.81 165 101 266 Pal 2.09 
N908NSeptee ce cuie a 62 57 91.93 86 50 136 2.38 2.19 
sinistral, alliivearsiiae. ene 421 288 68.41 360 289 649 2.25 1.54 
Dextral;all'years.....5.......- 350 238 68.00 308 225 533 2.24 1.52 
Sinistral and dextral, 1906...... 345 166 48.11 119 170 289 1.68 0.83 
LOO Tpepactoee 297 244 82.15 360 244 604 2.47 2.03 
1908...... 129 116 89.92 189 100 289 2.49 2.24 
All, sinistral and dextral........ 771 526 68.22 668 514 1,182 2.24 10S 
