58 VARIATION, DISTRIBUTION, AND EVOLUTION OF THE GENUS PARTULA. 
however, that the data are more valuable in a qualitative connection than in a 
quantitative respect, owing to certain inherent difficulties. Sometimes the young 
individual was clearly recognizable as a member of the same color-class as its 
parent, while in another case it might be assignable to a contrasted group with 
equal certainty; thus the fact is established that the color-types do not breed 
absolutely true and that they are mutually related in a real genetic sense. This 
is the qualitative result. When it is a question of the inter-relationships of very 
distinct types such as flavea and strigata, the features of contrast appear early and 
the figures are undoubtedly accurate for the two kinds of young taken from the 
parents of the one or the other class; in such cases the quantitative data also are of 
real value. But when pallida and flavea are under consideration, inevitable errors 
of observation arise, because the young shell is thin and pale in color as compared 
with that of an adult; hence it is not always possible to determine whether such an 
individual would continue light in color to become a pallida adult, or whether its 
tints would intensify with growth so as to make it an adult flavea. These con- 
siderations are to be kept in mind throughout the following discussion of illustrative 
cases, for which the specific data are given in table 24. 
TABLE 24.—Partula radiolata, Guam. Statistics of heredity of color-characters in representative colonies. 





















Gravid adults. Young. 
Colony. 
Color-class. No. pallida. flavea. fulva. strigata. tin i bicestata.| Total. 
‘Tafague...;¢2cr25 | pallidage: .. feds. som 19 19 11 Pet ae ae Sue 30 
flevee; ck hee et 30 17 19 36 
fulva 7 1 6 3 10 
Total 56 37 36 & Sea 76 
Cabras, cast... 2.2. | Saweate sok cd- see oes 7 eek 12 Ls a aeons 1Z 
atrigatns: «ou es ores 54 Ey 2 Rae 60 Z 64 
bicestata. acc cask) alas 33 seas 1 a ys 46 49 
| Tebal tes deen bhal sie | 15 62 | 48 125 
Cabras, west. .... flaved t.5°0.).2 ; Ree ii 3 Eh SKE 3 
Strigntns och i% soo cane 28 Re 45 ake 1 46 
strigata-helix........... 14 4 11 H 6 21 
bigestatascc. (e205 etn 10 vee 21 21 
a otale. . S43 aes 53 | a 49 11 28 91 
MOrotel i.e. wees pallida? 275. F20h Gea ae 18 7 13 a oor oa 20 
flaveasi#.-3 Sted Keo ke 33 4 39 3 Rete 46 
falva.?. Wether 18 3 29 ya rw, + ae 
etrighte a. <eossasetiue 43 7 7 51 65 
| bicestata: =... sarc 9 1 1 4 3 7 16 
ShGtal tet cata erse.s 121 RS 89 | 14 | 54 7 | 179 | 

The Tarague association comprises flavea, pallida, and fulva adults. The 
embryonic young of the first-named are yellowish 19 and whitish 17 (fig. 57, plate 
11); here there is only a slight preponderance of the flavea type among the off- 
spring. The 30 young borne by the pallida adults are yellowish 11 (fig. 58, plate 11), 
whitish 19, thus displaying a definite tendency toward the production of the lighter 
