12 University of Michigan 



genus Tudora on the island of Curacao, where the prominent 

 breaks in the limestone rim are accompanied by changes in 

 the shells themselves. On Curacao, the main station numbers 

 indicate those areas of the limestone which are most markedly 

 isolated by such natural boundaries, but, on Aruba and 

 Bonaire, sharp lines of demarcation can rarely be drawn. ^^ 



Curagao 



Although Curasao (Plate I, fig. 1) is only about 35 miles 

 long, it can readily be divided into three, quite distinct areas, 

 on the basis of the distribution of land molluscs. The first 

 of these centers about the Tafelberg of Santa Barbara (fig. 

 1, 2-B) ; the second includes the remainder of the southwestern 

 shore between Spaansche Baai (2-E) and Boca Sint Marie 

 (9-G), and the coast of Hato (10, 11, 12) on the northeastern 

 side; while the third is composed of the western shore north 

 of Bullen Baai (9-F) and the higher hills in the older rocks 

 (20). As already discussed, the many breaks in the limestone 

 rim of Curagao quite markedly isolate the various stations. 

 The more recent limestone is mainly limited to the shore 

 region southeast of Piscadera Baai (5-W). 



Station CI. Northwest of Neiv Port (fig. I, 1-A ; L68° 50.72', 

 12° 3.52').^* New Port is the harbor of the phosphate com- 

 pany ; it is situated on a rather broad shelf of recent limestone 

 along Fuik Baai. As this locality is on the leeward side of the 



13 Throughout this paper, the stations are designated by letters and 

 figures, as follows: C, A, B, and K stand for the islands of Curasao, 

 Aruba, Bonaire and Klein-Bonaire, respectively; these, followed by 

 b, c, or d indicate (b) the localities on the older deposits, and (c) the 

 freshwater and (d) marine habitats, as opposed to the stations on the 

 limestone. The figures give the station numbers; these are followed by 

 letters for the substations. 



14 After each station is given a reference to the map of the island con- 

 cerned (plates I and II), followed by the west longitude and north lati- 

 tude of the place mainly collected (indicated by the letter L). These 

 are measured to 1/100 of a minute on the Netherlands Government 

 1/20000 topographic maps, and thus locate the type localities within ap- 

 proximately 20 meters. 



