PARTULA NODOSA. gl 
tionate numbers of dextral and sinistral snails, when the latter are present; (3) by 
the relative numbers of either mode of coil that are assignable to the several color- 
classes; (4) by additional peculiarities in the matter of size, etc., that may be even 
more fundamental than the other differentia. 
On the basis of the above, four regional varieties will be established, to be dis- 
tinguished for practical purposes by proper names. ‘The first, var. composita, 
includes the shells of Garrett’s classical area, Punaruu, as well as those of Taapuna; 
the second, var. /eva [(Mayer) Pilsbry] occurs in Maruapoo; the third, exigua, 
occupies Atehi Valley only; the fourth, derived from the first and now inhabiting 
Papehue, Aoua, and Orofere Valleys, is genetically transitional from the first-named 
to the third, and may be termed intermedia. These varieties will be described in 
the above-stated order, and the Taapuna colony will be taken up first because the 
collection from that valley is larger than the Punaruu series. 
Partula nodosa composita var. nov.—Taapuna Valley. 
In 1906 the coastward portion of this valley yielded 158 adults of this species 
out of 182 of all kinds, or 86.8 per cent; in 1909 the interior part was explored, 
and out of 369 adults of all species, 155 or 42 per cent were nodosa. ‘These facts 
show that P. nodosa is more abundant in the lower levels than it is in the interior, as 
fewer specimens were secured during a longer period of collection on the second 
occasion. ‘They also indicate that the lower relative frequency in the remote parts 
of the valley is due to the greater abundance of P. otaheitana in the interior, for the 
absolute numbers of nodosa secured in the two years are virtually the same, yet the 
percentage of the whole population is much smaller in the second year’s collection. 
In detail, the four distinguishable color-divisions are as follows: 
Class I, pallidior Pilsbry: Plain, light, and unbanded shells with a white, whitish- 
yellow, or creamy ground-color, more or less streaked transversely with yellowish- 
brown (figs. 9, 10, and 31, plate 22). 
Class IT, trilineata Pease: Upon ground-colors like the above or on brownish- 
yellow backgrounds revolving bands are developed. The full number of bands is 
three: one median, one subsutural, and one basal, of which the first is usually more 
pronounced. ‘These bands vary from narrow and interrupted rows of spots to 
connected and progressively wider and darker lines of deep reddish-brown. White 
sutural areas are usually evident (figs. 11 to 21, 31, and 32, plate 22). 
Class III, concrescens Cr.: The subsutural and median bands are connected by 
similar color so as to form a broad revolving zone which is sharply delimited by the 
white sutural area and by the uncolored area between the basal band and the 
“median” component of the broad zone. The bands grade from light yellowish- 
brown to deep seal-brown or purplish (figs. 22 to 25, plate 22). 
Class IV, nodosa Cr.: The shell is unicolored, chestnut-brown, seal-brown, deep 
or light purplish-brown, with a white sutural area like that of Classes II and III, 
although this may be vaguely defined or even lacking (figs. 26 to 30, 34, and 35, 
plate 22). 
