PARTULA NODOSA. 97 
to 19 and 29 to 36, plate 23, and figs. 1 to 6, plate 24) are sometimes identical in 
coloration with Class II examples of var. composita, but as a rule the ground-color 
is a darker yellowish-brown or brown, the subsutural and even the basal band may 
be absent, and the sutural white zone is rarely developed. Light or dark reddish 
examples occur sporadically. Variations in size and shape are also evident, as the 
several illustrations demonstrate. 
The series of 1907 was obtained from the vegetation along the rough and rocky 
borders of the stream, in the lower valley. The first snails were found on Colocasia, 
a mile from the shore and about a quarter of a mile from the mouth of the valley, 
where the barometer registered a level of 400 feet; all were sinistral, and examples 
of P. clara or P. hyalina were associated with them. In 1908 more extensive collec- 
tions were taken in the forests above the steep cliffs that abruptly divide the valley 
into lower coastward and higher inland parts. Snails were found from 250 feet to 
goo feet altitude, the limit of exploration. Heavyrains had fallen for four consecutive 
days, and in consequence the animals were actively crawling about on all kinds of 
vegetation and even on the bare volcanic earth itself. This year specimens of 
P. otaheitana, P. clara, and P. hyalina were obtained, as well as dextral individuals 
of nodosa. 
The proportionate numbers of plain and banded individuals differ in the two 
annual series, neither of which agrees exactly with Mayer’s collection (table 43). 
In the lowland collection all are sinistral and the banded class predominates, while 
- in both the sinistral and dextral divisions of 1908 the plain color-type is more 
abundantly represented. 
TaBLE 43.—Partula nodosa leva. Maruapoo Valley. Classification of material. 
1907 (personal).) 1908 (personal). | 1899 (Mayer). 
Group. peer erage aera | 
No. |Per cent.) No. |Per cent.) No. |Per cent. 
Sinistral, plain. ...... 20 38.4 545 73.3 139 39 
Sinistral, banded..... 32 61.5 170 22.9 55 55 
Dextral, plain........ Ve totes: 17 2.3 14 4 
Dextral, banded...... a ates 11 1.5 2 2 
743 
lIncluding faintly banded individuals. 
The statistics relating to the Marupoo shells are given in table 44. The series 
of 1907 comprises individuals that are larger than the reversed group of 1909, and 
the differences are significant in all four of the direct measures; the former are 
somewhat stouter in shell proportions, while in aperture proportions and in the 
relative length of the aperture they show more decided divergence. 
The dextral snails of 1908 form a group with essentially distinct characters, 
but they do not tend to resemble the dextral colony of Punaruu, as they should if 
they were stragglers from that neighboring valley. They are undoubtedly relatives 
of their reversed associates, even though they differ from the latter in statistically 
definite degrees. 
