158 VARIATION, DISTRIBUTION, AND EVOLUTION OF THE GENUS PARTULA. 
for both classes of adults, but the proportion of young snails is higher in the red 
class. This means only that the latter kind of adult begins to reproduce earlier, 
and hence bears more numerous advanced young at the seasons when the present 
material was collected. 
TaBLe 97.—Partula otaheitana rubescens, Papenoo Valley. Statistics of heredity. 
1906. 1908. 
Yellow young. | Red young. Total. Yellow young. Red young. Total. 
Yellow adults..... 1 3 4 [26.6 p.ct.] | 16 6 22 [18.5 p. ct.] 
Red adults....... 2 9 11 [73.3 p. ct.] | 56 41 97 [81.5 p. ct.] 
Totalivn.t...soer 3 [20 p. ct.] 12 [80 p. ct.] 15 72 [60.5 p. ct.] | 47 [39.5 p. ct.] | 119 
1909. All years. 
Yellow young. | Red young. Total. Yellow young. |} Red young. Total. 
Yellow adults..... 51 15 66 [37.9 p. ct.]} 68 24 92 [29.8 p. ct.] 
Red adults....... 55 53 108 [62.0 p. ct.]} 113 103 216 [70.1 p. ct.] 
Motalis Sateen 106 [60.9 p. ct.]} 68 [39.1 p. ct.] | 174 181 [58.7 p. ct.]} 127 [41.2 p. ct.]}| 308 
TaB_LeE 98.—Partula otaheitana rubescens, Papenoo Valley. Percentage of yellow type in adult and 
embryonic populations. (Red type equals 100 per cent minus the figures for yellow.) 
Adults. 
Embryonic 
Series. Percentage | Percentage Percentage Percentage young, 
F ; : bearing bearing per cent. 
in popula- | in gravid 
tion. population yOuUne young 
“| taken once. | repeated. 
1906, yellow..... 27.14 37.50 28.57 26.66 20.00 
1908, yellow..... B33 5383 20.00 21.75 18.49 60.50 
1909, yellow..... SOR 40.12 37.73 37.93 60.92 
All yellow....... 
The statistics of heredity (table 97) are astounding, on account of the great 
preponderance of yellow individuals in the embryonic series. Only a few snails of 
the 1906 collection were gravid, and their young conform closely to the adults in 
regard to the relative numbers of yellow and red individuals. But in the other two 
series, while the yellow adults naturally produce a larger proportion of similarly 
colored snails, the red adults bear yellow young in more than 50 per cent of the 
cases. The result is a great excess of yellow young as compared with the relative 
number of yellow adults in the whole population, in the gravid class and in that 
section of the gravid group which bears advanced embryonic young, whether these 
last-circumscribed adults are taken once only or once for each of their classifiable 
young (table 98). The figures in the fourth column are slightly lower than those 
in the first, for reasons given above, which relate to differences in the rate of 
production of the yellow and red classes. But when all allowances are made, the 
high figures for yellow young produced by the 1908 and 1909 series indicate a fact 
of real consequence. 
