284 VARIATION, DISTRIBUTION, AND EVOLUTION OF THE GENUS PARTULA. 
Passing to heredity (table 238) it appears that no young were found with bands; 
in view of the lightness of the stripe, even in the adult, it must escape detection 
in the very few cases of sporadic cestata young. As far as the “plain” class is con- 
cerned, it is significant that the proportionate numbers referable to the three color- 
groups are much the same in parental and offspring series. On the basis of the 
facts as observed and recorded, the color-composition of the prevalent unbanded 
class seems to be stable from year to year. 
TaBLe 238.—Partula otaheitana crassa aberrans, Taapuna Valley. 
FEcunplirTy. 
No. of | Per cent} No. of | No. of Total Average | Average 
‘| gravid.| gravid. }| eggs. | young. | contents. | for gravid.| for all. 
1906, plain........ 9 4 44.4 1 3 4 1.00 0.44 
1909, plain........ 178 145 81.5 214 136 350 2.41 1.97 
1909, banded...... 3 z, 66.6 3 2 5 2.50 1.67 
ICO; Bo sosboooac 181 147 81.2 217 138 355 2.41 1.96 
HEREDITY. 
Young, plain. 
————E—E Total. 
Light. | Medium.| Dark. 
Adults: 
Plain wlightaeemeeneeie 10 3 ye 13 
mediumerereer 10 26 20 56 7136 
darkitiscatocahec 6 21 40 67 
Batid edeeieanerernerirts 1 1 2 
Eotal nisin scrote 26 51 61 138 
ss FS Or 
138 
SUMMARY AND CONCLUSION. 
I. Partula otaheitana crassa 1s the third member of a southern and western series 
of primary varieties composed mainly of sinistral individuals with brown shells, some- 
times bearing revolving bands. Virtually all of its characters are displayed by some 
of the members of the basic stock existing in Fautaua Valley. Its affinities with 
otaheitana sinistralis are closer than with otaheitana sintstrorsa, in correspondence 
with the geographical relations of their areas. 
Il. The primary variety 1s differentiated more clearly than are its near relatives 
into subordinate groups, two of which deserve distinctive names. The fundamental 
crassa stock is interrupted in its range by a wedge including two valleys that are 
inhabited by the peculiar crassa occidentalis, while again at its northern limit it 
appears in the novel colony of aberrans, distinguished by such diverse features as 
its color-composition, size of the shell, and form of the egg. The boundaries that 
mark the subsidiary areas of these secondary divisions do not correspond with those 
which delimit the spheres of the primary varieties of Partula nodosa, a species that 
inhabits seven of the same valleys. 
