CHAPTER III. 
PARTULA SALIFANA, new species. 
The discovery of a new species of Partula was entirely unexpected, in view of 
the extensive investigations in Guam by such collectors as Quadras and Rush in 
recent decades, Garrett and Cuming a half-century ago, and Gaudichaud-Beaupré, 
Quoy and Gaimard, and Lesson in the earliest years of the scientific exploration of 
the Mariana Islands. So far as observation goes, the new form is sharply restricted 
to the summit of an isolated height in a remote and rarely visited part of the 
island; hence it is not excessively remarkable that the species has not been secured 
hitherto. It is a detail of interest perhaps that the novel snails were discovered in 
the course of the very last field trip in Guam to an area of relatively high bush 
on the summit of Mount Salifan which had attracted attention from a distance 
during other journeys about the coast. The ascent over the wet and slippery foot- 
hills was accomplished on the back of a carabao or water-buffalo, with an unusual 
amount of attendant discomfort and protracted after-effects. 
The species is not abundant in its area of habitation; 19 adults in all were 
taken, together with 3 adolescent individuals, in an area of a few acres of bush 
growth just below the peak of Mount Salifan. The grown specimens constitute 
16.1 per cent of the adult Partula population, their associates being the usual gibba 
and radiolata (see table 4). From the gravid snails, 26 eggs and 28 embryonic 
young were secured; the latter, like the partly-grown specimens, prove to be par- 
ticularly valuable for the interpretation of the color characters of the species. 
The requisite formal description is as follows: The shell is dextral, ovate-conic, 
with the spire somewhat protracted, and it presents the general appearance of the 
basic species of the Society Islands, in contrast with gibba and radiolata of its own 
island. The umbilicus is open and slightly flattened. In substance the shell is 
thick and heavy, again as in the Society Island species. The whorls are 5 to 5%, 
slightly impressed below the suture. The embryonic whorls are closely engraved 
and their spiral lines are continued on the older whorls with wider spacing and 
lessening distinctness; about the umbilical depression at the base of the last whorl 
these lines are more deeply incised and more closely crowded. The mature cortex 
is smooth and shining, as if varnished. The color is a rich chestnut-brown or seal- 
brown, with a yellowish or olive cast in one specimen; as the result of decortication 
the color changes to purple, beginning with the apical whorls, and hence the 
general age of a shell is indicated by the extent of the purple modification. The 
extreme apex is deep purple in color in some instances. The interior of the last 
whorl is shining and purplish in color in all specimens. The aperture is elongated. 
The lip is well expanded and flattened, and its outer portion gradually narrows as it 
approaches its contact with the upper whorls; at the umbilical insertion it is broadly 
flattened and almost channeled. By the inward production of the lip the aperture 
is contracted to a noticeable degree. The color of the lip varies; in one specimen it 
is white, in the others it is pale yellowish brown, pale purplish, or both purple and 
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