COLLECTIONS FROM GUAM AND SAIPAN. 21 
is more sparse and of lower growth; on Tahiti no Partule at all would be found in 
such situations as the thickets of the outer Presidio (plate 5 B) or the bush back of 
the town of Agafia (plate 6 B). 
The localities of the South Central Region are on the higher ground in almost 
all cases. Above Asan (plate 5 a) and above Fonte the vegetation is fairly thick, 
as on the northern plateau. The Macajna localities were situated on the lower 
slopes of the mountain of that name, with more open thickets of Pandanus and its 
associates. Near Ordot the snails were taken on almost isolated stands of Pan- 
danus, or from the fringes of open thickets. At Pago North, so-called, the bush 
was thick and at least 200 feet above sea-level; the conditions in the case of the 
Upper Ylig locality were about the same. The Pago River and Lower Ylig collec- 
tions were taken in the gorges of the respective streams at very low altitudes. 
Finally, the Lonfit locality was of intermediate level, adjoining the lower Pago on 
one side and the higher ground of the Ordot locality on the other. 
Returning to the western side of the island, the Apra Region comprises three 
localities; two of these are areas of continuous vegetation on Cabras or Apapa 
Island, which is composed solely of rough, eroded limestone. The Orote locality is 
much higher, perhaps 400 feet above sea-level; its bush is like that of the northern 
plateau, but not quite so thick. The rock of the high Orote Peninsula is uplifted 
reef limestone. Otherwise in this region the bare westward slopes of the Tenjo 
ridge and the coconut plantations along the low borders of Apra Harbor are 
distinctly unsuitable as habitations of Partule. 
In the West-Central Region the small Agat collection represents the thicket 
populations of low altitudes, as in the Coast Central localities. Here again it is 
noteworthy that no snails would be found under such circumstances in the Society 
Islands. On Mount Salifan the bush is thick near the summit, where it is isolated 
on all sides, except the south, by the extensive savannas or “‘ mesetas”’ which occupy 
so much of the area of this whole region (plate 4, a and B). 
Like the coastal areas of the Apra Region, the lower ground of the Southwest 
Region is not habitable (see plate 3, B andc). Only the higher levels above 300 feet 
altitude bear vegetation of a suitable growth, which rarely surpasses a thicket in 
density. Snails were secured at three places on the heights to the east of Umatac 
Bay, namely, Salonga, Pajom, and Madog. To the east of Merizo on the south 
coast, the valley of the Geus River cuts into the southwestern section of the moun- 
tain range, and here also the vegetation was relatively low and sparse. The locality 
is named from the adjacent village of Merizo. 
The last region is the Southeastern. This is the territory which comprises the 
rolling eastward slopes of the high mountain ridge. Long river courses are cut in 
these slopes, and for the most part the habitable vegetation is restricted to the 
immediate neighborhood of such streams. The intervening ridges are bare savannas, 
or they possess a scanty growth of scrub and brush. Various circumstances pre- 
vented a personal visit to this region, but a series of snails was procured by a reliable 
assistant from the lower canyon of the Inarajan River. While a complete series of 
collections from all river gorges between Inarajan and the Ylig would be desirable, 
