PARTULA HYALINA. Bis 
(1) It is well established by the comparative study of Polynesian tradition that 
the Cook and Austral Islands were peopled from the Society Group. But whichever 
one of the two groups was the stepping-stone from Tahiti to the other, the fact 
remains that numerous voyages were made by the natives in their outrigger canoes 
to and fro among these three groups. The traditional history of the natives is full 
of accounts telling of military expeditions for conquest and pillage. In one case 
in my knowledge, the tale recites the hardships of natives sent from Tahiti by a 
priest during a time of famine, to procure food from “an island in the South,” which 
they found and which is now identified with one of the Austral Group. As the 
people of the flotilla must needs have taken food-supplies, it is conceivable that 
snails of this species, sealed up upon a cluster of plantains, might have been carried 
alive to a new locality, where they may have established their kind. 
Militating against this explanation, however, is the absence of hyalina from 
Moorea and other islands near Tahiti, and from Aitutaki, Atiu (and Rarotonga?), 
which are neighbors of Mangaia and Moki. ‘The intercourses of natives belonging 
to different islands of one group must have been closer and more frequent than in the 
case of the three groups taken as units, on account of the numerous intermarriages 
and wars of which records exist. It is not probable, therefore, that hyalina would 
be carried to a far distant group in infrequent communication with headquarters 
when the species is absent from islands in close proximity that were visited more 
often. Latterly the development of modern methods of trade has greatly facilitated 
intercommunication among the islands of each of these groups, yet no case appears, 
either in Garrett’s experience or in my own, where natives have transplanted a type 
from one island to another, even from Tahiti to Moorea or vice versa. 
(2) The contention that hyalina is an ancient type remaining in certain of the 
peaks formerly belonging to a continuous land-mass, suggested also by Pilsbry, is 
involved with the doctrine of subsidence. It is firmly supported by the evidences 
relating to other species of Partula, considered beyond. Against this contention 
two considerations may be urged, the first of which is biological, while the second is 
geological in nature. 
It may be argued that if hyalina was a widespread species before the present 
islands of the Society Group were isolated, this species ought to be found in some 
of the other elements besides Tahiti. It is true that the environmental conditions 
are the same in all the larger “high” islands of this group, at least in so far as their 
effects upon hyalina are concerned; this is clear from the occurrence of hyalina in 
drier and wetter and in higher and lower stations of Tahiti which find their counter- 
parts in Moorea and other neighboring islands. If the second interpretation of the 
history of hyalina is correct, we must conclude that the species did exist at one time 
in what are now Moorea and Raiatea and the rest, but its colonial variation was 
such as to result in the extinction of the species in all of the islands except Tahiti. 
We have learned from the analysis presented in the foregoing sections that hyalina 
varies much in different valleys of Tahiti, in structural respects as well as in 
its innate vigor. Even if we should ignore those stations where the species are 
not found, and focus our attention on the positive data, it appears that in an 
