PARTULA GIBBA, GUAM. 97 
with mitella mates is indicated. Furthermore, the type a young of mitella adults 
far outnumber the type 4b young; judging from the facts in the case of such asso- 
ciations as the upper Ylig, many of the former are certain to become mitella adults, 
but without question others are destined to remain light and to develop into 
unicolor or bicolor individuals. Hence the evidence is strengthened that the classes in 
question interbreed. 
The darker adults of the mitella-rubra and phea classes contribute recruits to 
the lighter color-groups; as the adolescents of these two types show no real dis- 
tinctions, it is not surprising that their type c young are not distinguishable. It is 
interesting that the total number of the deepest-colored young is 23, which corre- 
sponds closely with that of the two groups of darkest adults, namely, 28. 
TABLE 49.—Partula gibba, Guam. Statistics of heredity of color in representative associations. 





Young. 
Locality. Gravid adults. 
y : Tepes Type b, Type ¢, 
hare yellowish, brown- Total. 
be! : tinged apex. corneous. 
OTAGO eps terete te WNICOION. cee ee sis 79 79 
DICOLOR joyiraiahe Satake ith 88 88 
MUCOUS sea iecicds ea 82 6 1 89 
mitella-rubra........ 7 18 25 
Dia ace eda 3 4 a 
PPotalyct. enin- 259 6 23 288 
Santa Rosa..........| mitella..... 16 10 1 fH 
as eto Stes ory eee = 3 45 48 
A OUA Late tes 16 13 46 75 
Rarwgarda mcs ee . Mibel leer see, 2 tae 4 21 25 
mitella-rubra........ 1 7 8 
heen eae ec ariee ee 16 4 9 29 
WEOPETA ts). bok. Ga het 79 ah ah 1 80 
Letale erase. 100 32 10 142 
PIN CAS oe achat mrartella cero ost oh aysot 34 34 
mitella-rubra........ Zz 2 
marginata........... 7 7 
LOtalla tte ke « 36 Pea ate 7 43 





The Santa Rosa series is useful because its adults are mitella (25) and phea 
(46), together with one sporadic bicolor; the young are recorded in table 49. Allow- 
ing for the probability that some of the type a among the offspring of mitella might 
become bicolor, most of them would assuredly develop into mitella adults. Very 
few of the young of phea are other than type c, but enough belong to type 0 to 
justify the conclusion that they would grow into mitella adults. By virtue of such 
mutual contributions, the light young of types a and b come to number 29 and the 
dark young amount to 46, which numbers agree remarkably with those of the two 
contrasted kinds of adults as specified at the beginning of this paragraph. 
From the comprehensive table (table 48) it appears that the young of castanea 
are mainly of type a, about one-quarter are type J, but none is typec. Surely some 
