Proceedings

The known moss flora of the small West Indian island Saba (870 m in altitude) consists to date of48 species, while the neighbouring island St. Eustatius (600 m) has 40 species. The two islands have 27 species in common. Widely distributed neotropical species dominate at all elevations, while wide-tropical (i.e. pantropical) species are found mainly at middle elevations (300-600 m). Species with smaller geographical distributions (southern neotropical, Caribbean) are restricted to higher elevations (above 600 m).

An attempt has been made to determine the relation between mosses and the plant communities, encountered along the altitudinal gradient, by calculating “association values”, based on the results of random collecting. Four classes of association values have been distinguished: class A: very characteristic; class B: characteristic; class C: moderately characteristic; and class D: non-characteristic species. It appears that eight plant communities on both islands harbour one or more moderately to very characteristic species. Neckeropsis undulata is the only very characteristic species. It occurs in the evergreen seasonal forest on St. Eustatius. The results are compared with Guadeloupe, Martinique, Puerto Rico, Guyana and Suriname. Finally, a key to the species is included.

In 1942-1943 a water test well was drilled by the Government of Curacao within the limits of Aruba's capital Oranjestad, following the "discovery" of an underground fresh water flow by two French friars operating a detector or divining rod. A depth of 927' was reached without encountering the predicted fresh water. However, abundant salt water under pressure was stuck in a sand bed at 830'. Its salt concentration proved to be twice that of sea water. It may be assumed that rain water enterig the outcrop area of weathered diorite and diorite detritus further inland, percolates down through a dipping sand bed, locked in impervious clay layers, thus constituting an artesian water system. The high salinity of this water is tentatively explained by a process of solution of salts adsorbed in the sands and clays during their deposition in a marine or coastal environment.