254 VARIATION, DISTRIBUTION, AND EVOLUTION OF THE GENUS PARTULA. 
unusual types) and the one called striata, which is characterized by sharply defined 
dark strigations upon a lighter background (plate 32, figs.9 to11). The latter class 
was suggested by certain of the bandless shells of the Tenaire sinistrorsa colony. 
Statistically (table 199) the shells are collectively different from those of Teohu, 
being even more abbreviated but not more tightly coiled. The apex class resembles 
the associated groups of the same valley more than the same class of Teohu. 
Taken in March 1906, the fecundity (table 200) of the colony is naturally low; 
the recent resumption of breeding activity is the cause. 
In the figures for heredity (table 200) the unbanded classes are united for com- 
parison with cestata. The number of banded offspring is smaller than the number of 
gravid adults, which indicates a late manifestation of the characteristic bands. 
TaBLe 200.—Partula otaheitana sinistralis. Papeiti Valley. 
FECUNDITY. HEREDITY OF PATTERN. 
J | J 7 7 
Series Records! No. of | Per cent No. of | No. of | Total Ay erage Average|} Young, | Young, Total. 
gravid. gravid. | eggs. | young. | contents. |for gravid.| for all. || unbanded.| cestata. 
Unbanded classes. 265 198 74.7 259 70 329 1.66 1.24 63 7 70 
cestatals ma thio: 209 150 71.8 214 40 254 1.69 i Ail 20 20 40 
US OOO eS OpIGIOT 474 348 73.4 473 110 583 1.67 1.23 83 27 110 
TEMARUA VALLEY. 
In making the collections here during the summer of 1908, all the snails were 
taken in the middle and upper part of the valley so as to secure a series from a 
territory that was well cut off from the Papeiti region. Out of 563 adults, only 
one was an apex shell, although two similar specimens of partial growth were 
found; none of them showed any indication of decortication. ‘The phea class is not 
differentiated into striata and confluens subdivisions, but is continuously variable, 
although scarcely any shells exhibit the sharply defined strigations of so many 
Papeiti individuals; of the specimens illustrated (plate 32, figs. 16 to 19), that of 
figure 16 is unusual in having a clear revolving area below the suture, while those 
of figures 17 to 19 are aberrant in particulars of size or form. 
The cestata class falls into two divisions, which merge into one another through 
transitional individuals; in one of these the bands are clearly and boldly marked, 
while inthe other (plate 32, fig. 20) heavy dark strigations partially obscure the stripes. 
Two dark dextral shells of this color-type were discovered (plate 32, figs. 21 and 22). 
Statistically (table 201) this colony proves to be much like that of Papeiti. 
The color-classes differ very little from one another. The two dextral specimens 
are quite unlike, which would point to their independent origin by mutation from 
sinistral parents, rather than to their genetic relationship. 
The fertility of the colony is high (table 202) as compared with that of Papeiti, 
on account of the seasonal difference in the time of collection. The cestata class 
displays a somewhat higher rate of productivity, but the difference is not very great. 
