100 VARIATION, DISTRIBUTION, AND EVOLUTION OF THE GENUS PARTULA. 
25 yards of the ocean, thus resembling the animals of such a station of Guam as 
the outer Presidio locality. 
Fanaganam, the next locality, is a well-wooded hill about 250 feet in altitude, 
situated to the east-northeast of Garapan—the main settlement of Saipan. In 
ecological respects it agrees with Sadog Tase, and it is well cut off by plantations 
from the coastal thickets, like those of Puntan Flores. 
Torre, “the hill,” is a similar but smaller upland east of Garapan, from which 
collections were secured for the sake of comparison. 
Astaman is a higher collecting-ground, at least 500 feet above sea-level, on 
the westward slopes of the main mountain mass, and nearly west of the summit 
of Mount Tapochau. Its rock is still limestone, very rough and eroded, with a 
fairly thick growth of trees. The animals were not found in abundance in that 
place, despite the heavy rains of the time. 
The station called Garapan is another lowland locality with hedge plants 
and shrubs, immediately to the south of the town sonamed. It was here that 
the first collection was made. 
The last station in geographical order is Chalankiya, situated about 3 miles 
south of Garapan on the flat coastal plain, but at some distance back from the 
strand. This region is the most open anywhere found as the habitation of Partule 
(plate 9, A). The snails were adhering to the leaves of all kinds of trees even 
when such trees were isolated, while their numbers were greater on the thicker 
vegetation of the lower scrub. The caladium leaves were especially favored, 
and in one case 31 animals were found on the under side of a single leaf of the plant 
(plate 9, B). 
In summary, the 8 localities under consideration (plate 10) extend over a 
total distance, north and south, of 6 miles on the western side of the island; 4 
are lowland stations—Puntan Muchut, Puntan Flores, Garapan, and Chalankiya— 
while the others are upland forested regions. The soil in the case of the first group 
is alluvial, while at the other and higher places the exposed rock is limestone. 
The material from the 8 areas of collection in Saipan comprises 2,666 adults 
and 664 partly grown individuals; 3,368 young and 4,816 eggs were dissected out 
of the former, thus providing an abundance of embryonic items for use in connec- 
tion with certain problems. Departing from the order of treatment of the previous 
chapter, we will deal first with the qualitative characters of the color-classes, and 
then take up the statistical analysis of the collections. 
But first there is a general feature of the Saipan gibba which demands early 
recognition. It is the rule in Partula that the shells attain their maximum size, 
density, and coloration, and form the flaring lip about the aperture at the same 
time that they become mature in the reproductive sense. We have seen that 
Partula fragilis is unique in that the late adolescent snails reproduce before they 
develop the lip. ‘The gzbba of Saipan display the antithetic relation; they gain their 
full size and form the flaring lip before they proceed to mate and to bear young. 
Any series of full-sized shells provided with lips is readily assorted into two 
groups, in one of which the texture is thinner and the colors are lighter; both of 
