PARTULA OTAHEITANA. 169 
The statistics of heredity (table 113) disclose certain interesting facts. In the 
first place, the class of yellow-white adults (I) is not represented in the embryonic 
series; wherefore it is evident that the distinguishing coloration is a modified one, 
becoming manifest only during post-embryonic life; without doubt Class I shells 
are embryonically of Class II, but change later through decortication. Aside from 
the above qualification, each class produces its own kind and representatives of the 
other groups as well. Summing up by combining Class II with Class I, and Class 
III with Class IV, so as to have the two primary divisions of “yellow” and “red” 
individuals, the numbers of young snails assigned to those two divisions prove to be 
TaB_e 113.—Partula otaheitana rubescens, Oopu Valley. 
Statistics or HEREDITY IN FULL. 
Young, yel- Young, Young, red- Young, 
low-white, I.| yellow, II. | orange, III. red, IV. 
Adults: 
Yellow-white, I, A 
B 
Yellow, II, A 
B 
NR NNO PON 
2 
1 
1 
9 
8 
3 
4 
3 
HEREDITY OF GROUND-CoLor. SUMMARY. Herepity or Apex-CoLtor. SuMMARY. 
Young, | Young, , | Young, 
yellow, red, Total. dark Total. 
I, Il. III, IV. , A. | apex, B. 
Adults: Adults: 
Yellow, I, II A, clear apex..... 
Red, III, IV B, dark apex..... 
almost equivalent to the numbers in the corresponding groups of adults; the differ- 
ence of only 9 in a series of 267 is very slight. When we consider the heredity of 
the deeply-tinged apex, we find a greater discrepancy; the plain-tipped adults pro- 
duce a large number of similar young, but the dark-spired adults also bear an astonish- 
ingly large percentage of young with the plain apex. The total number of Type A 
shells is so greatly in excess of the contrasted type that we must assume a late 
appearance of the apical coloration in the majority of individuals destined to have 
this character as adults. The ease with which the apical darkening can be seen 
even in young embryonic shells (plate 28, fig. 18 B) serves to remove the objection 
that errors of observation have been made. Assuming that the facts are correct in 
