Occasional Papers of the Museum of Zoology 21 



Stations Chi? and 20 }"" Sint Christoffelberg (372.44 meters), 

 the highest peak in the Dutch Leeward Islands, is the climax 

 of a much dissected mass of sedimentary. Cretaceous rocks, 

 which outcrop in a complex series of folded and twisted 

 laminae. The leeward slopes of these hills, and especially the 

 narrow valleys that open to the north and west, are the most 

 heavily wooded places in the islands. Especially conspicuous 

 are the large clumps of the yellowish-green Bromelia lasia^itha, 

 which holds water in its sheathing leaves, and may carpet 

 areas several acres in extent. In the richer valleys, and 

 especially near the top of the western side of Sint Christoffel- 

 berg, epiphj-tes {Tilkbndsia utriculata, etc.) and lianas (Ficus, 

 etc.) increase the luxuriance of the foliage, until it presents 

 an aspect very different from the usual arid lowlands of the 

 islands. In the broader valleys (fig. iii-6), the divi-divi and 

 acacias attain a larger size than elsewhere, and, with the 

 organ-pipe cactus and Opuntia, often form quite impassable 

 thickets ; the larger trees are also more abundant on the hill- 

 sides. Peculiarly enough, the land molluscs, with the excep- 

 tion of Drymacus virgulatus, bury themselves deeply in the 

 rock talus, although the same or similar species may aestivate 

 on the brush and trees in much less humid situations. 



ChlTa. Valley hetiveen Seroe Bientoe and Seroe Palomha 

 (17-C; L69° 9.47', 12° 20.29')- This steep-sided, west-facing 

 valley between Windy Mt. (224.8 meters) and Dove Mt. 

 (163.1 meters) is almost choked with brush (fig. vii-19), but 

 is more barren than the next. 



Cl)17l). Valley between Seroes Palomha and Balia Hoendoe 

 (L69° 9.10', 12° 20.34'). This north-facing canyon was col- 

 lected during a rainstorm, when the molluscs were moving 

 around on the surface; for this reason, the shells appeared 

 much more abundant than in the other localities examined. 

 However, this was the most heavily wooded valley visited. 

 Most of the shells were obtained near its mouth, but Drymaeus 



19 Compare Boldingh, p. 157; "Christoffelberg"; aud K. Martin, I, 

 pi. X, XI and XTI. 



