PARTULA OTAHEITANA. 257 
The statistical description of the three associations (table 203) is valuable, as 
it defines the characters of shells that are geographically intermediate between the 
Temarua colony and the fuller series of sinzstralis in westward valleys. The large 
size of the Opiriroa shells is the most notable point of the inter-valley comparison. 
As a class, cestata is sometimes smaller and sometimes larger than its associated group 
in the same valley, but the two divisions of any one colony are far more similar 
than the cestata classes of two contiguous valleys, or two confluens groups of different 
localities; the figures for the shell proportions illustrate this point most clearly. 
In fertility (table 204) the figures are all somewhat below the average for the 
summer season. ‘The snails were not found in abundance, and hence the rate of 
productivity would naturally be less than in a numerous and more compact 
association. 
TaBLe 204.—Partula otaheitana sinistralis. Vaipoo, Tearatapu, and Opiriroa Valleys. Fecundity. 
No. of | Percent | No. of | No. of Total Average Average 
gravid.| gravid. | eggs. | young. | contents. | for gravid.| for all. 
.61 
47 
.29 
Tearatapu, unbanded... ; : .80 
banded : : .60 
.70 
Opiriroa, unbanded ; : .87 
banded : : 45 
.50 
The data of heredity (table 205) prove the genetic interrelationships of the 
contrasted color-groups. The figures give the facts as observed, but undoubtedly 
the preponderance of unbanded young in Opiriroa, for example, means that the 
bands develop later, and not that a change in the constitution of the colony is 
coming about. In Tearatapu the bands appear early. 
TaBLe 205.—Partula otaheitana sinistralis. Data of heredity. 
Vaipoo Valley. Tearatapu Valley. Opiriroa Valley. 
Young, | Young, 
Young, | Young, | 7p o44), || Young, | Young, plain. | banded 
plain. | banded. plain. | banded. Total. 
Total. 
23 
Otuna VALLEY. 
The sinistralis series taken in Otuna during the wet season of 1906 comprises 
346 adults and 87 adolescents. With this material it is profitable to undertake a 
more detailed analysis of the color-types. As before, shells of the cestata class out- 
