I50 VARIATION, DISTRIBUTION, AND EVOLUTION OF THE GENUS PARTULA. 
ation in Hamuta Valley, although each of them by itself is composed of subordinate 
types which do display genetic and morphological relationships similar to those of 
the components which constitute a single amabilis association. For practical pur- 
poses, it is clearly necessary to take up rubescens by itself and to pass over the affinis 
division for the time; the parallel consideration of both of these sections, in geo- 
graphical sequence, would lead to great confusion. 
Reeve’s description of rubescens is as follows: 
“Shell acuminately oblong, rather thick, sinistral, compressly umbilicated; whorls 6, 
smooth, somewhat rounded, lip and columella broadly reflected. Pink, red-brown towards 
the apex.” 
Garrett presents the following significant statement concerning this form and 
its distribution: 
“Reeve’s rubescens=turricula is abundant in Papinoo,’ and occurs sparingly in all 
the valleys as far as the southeast end of the island. Like amabilis “it can not be separated 
from the sinistral turreted otaheitana inhabiting Fautaua. It is always sinistral, never 
banded, and, though usually of a reddish tint, is frequently straw-yellow or fulvous, with or 
without a reddish or pinky apex. Though described as edentate, some have a small parietal 
tooth. Reeve gave no locality, and Pfeiffer erroneously cited the Marquesas as its habitat.” 
In the collections of some museums, strikingly banded specimens of sintstrorsa 
have been included in representative series of rubescens; really they are entirely 
different and belong to a distinct primary variety. The matter of the columella 
tooth is important, for, as Garrett states, some specimens possess this structure, but 
only in the colonies of certain valleys; ordinarily the shells are utterly edentate. 
While the major characters as given in the above citations from Reeve and 
Garrett are repeated with substantial faithfulness in all of the valleys where rubescens 
occurs, marked differences in the make-up of the colonies appear on even a cursory 
examination. In some instances the light yellow shells preponderate, while in 
others the reddish members exceed them in number; sometimes a smaller or larger 
average size constitutes the colonial character. In other cases, a unique feature 
like the pillar tooth already mentioned, or a very unusual kind of bicolored marking, 
appears as a distinctive peculiarity of the shells of a single valley association. 
A general description of rubescens as a whole, covering all of the varied colonies 
of Tahiti, enumerates characters which are identical with some and with some only 
of those exhibited by P. 0. otaheitana, the parent stock as it exists in Fautaua 
Valley; the other unit qualities do not appear. In comparison with the list and the 
combinations as given in the general description of the species, rubescens displays 
the following features: 
Coil: sinistral always, dextral lacking. 
Size: large, with only one or two exceptional mutants. , 
Ground color: yellowish, reddish, or rarely intermediate between these; never brown or 
strigated. Never banded. 
Apex: may or may not be deeply tinged, varying in percentage in different valleys. 
. Surface: very smooth and shiny, never closely corrugated. 
1Misspelled throughout Garrett’s memoir. 
