CHAPTER VII. 
PARTULA GIBBA—SAIPAN. 
GENERAL CONSIDERATIONS. 
Toward the end of July 1920 the field-work in Guam was interrupted by a 
journey to the island of Saipan, about 120 miles to the northeast, for the purpose 
of securing representative series of Partula gibba from that territory. After the 
requisite permission for the visit had been procured from the Foreign Office at 
Tokyo, the writer accompanied by his son proceeded to Saipan and later returned 
to Guam on a small naval vessel attached to the station, made available by the 
interest and courtesy of Governor Wettengel. It was hoped that the intermediate 
islands of Tinian and Rota could also be explored, because the former, like Saipan, 
is reported in the literature as a habitat of gibba; but hurricane weather and other 
adverse circumstances made it impossible to land on either of the islands. 
During the six days of the sojourn in Saipan, snails were taken from eight 
characteristic stations on the western side of the island. The animals were found 
in extraordinary abundance, and their collection was facilitated by the prevailing 
typhoon weather of the entire period; the overcast skies and almost incessant rains 
stimulated the animals to greater activity and kept them from retiring to the seclu- 
sion which they seek on dry and sunny days. Yet the same climatic conditions 
prevented a more comprehensive study of the island. While a complete map of the 
varietal distribution of gzbba in Saipan can not be made, nevertheless the material 
is most interesting both on its intrinsic merits and also on account of its general 
relations to that of Guam. 
The geographical position of Saipan and its geological nature have been 
sufficiently described in Chapter II. The principal points are that the island is a 
single unit in general contour (plate 8, a), that only the highest portions consist 
of volcanic materials while the greater bulk is composed of uplifted reef-limestone, 
and that the massif possesses relatively abrupt borders except on the western 
side, where a definite coastal plain exists (plate 9). The culminating peak of 
Mount Tapochau rises to 1,530 feet above sea-level. 
The northernmost collecting station was Puntan Muchut near Tanapag 
Harbor (plate 10). On the flat land only a few score yards from the shore the 
animals were found in profusion in the thickets along the roadside. Among the 
dominant plants in that place were the hedge-plant called “camochili”’ (Cyclobza) 
and the customary “lemoncito” (77r1phasia). 
Next in order was the upland designated Sadog Tase from a small stream of 
the locality. The collecting-ground was forested and about 150 feet above the 
sea, and its rock was the typical limestone “cascajo” like that of the northern 
half of Guam. The general nature of this region and of its drier coastal border is 
indicated by the illustration (plate 8, B). 
Puntan Flores is again a flatland station like Puntan Muchut, and its vegeta- 
tion is similar to that of the first locality. The snails were found actually within 
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