114 University of Michigan 



the presence of Tudor a megacheilos (4 subspecies) and 

 Brachypodella raveni raveni. 



The northern area (C13-20) was probably populated from 

 the Sint Christoffel complex, which undoubtedly was formerly 

 fringed or covered by a limestone reef, such as is still present 

 on the Tafelberg of Sint Hyronimus (C20). This region is 

 differentiated by Tudora muskusi (3 subspecies), Guppya 

 molengraaffi, 3 subspecies of Tudora fossor, Brachypodella 

 raveni knipensis and Cerion uva knipensis. 



Neosubulina gloynii and Microceramus honairensis curacoa- 

 nus occur throughout CuraQao. The northern and central 

 areas agree in the occurrence of Cistulops raveni raveni, while 

 the central and southern possess Cerion uva uva in common. 

 The presence of the section Tudorata, and the resemblance of 

 the subspecies of Brachypodella and the species Tudora fossor 

 and pilshryi, appear to relate the northern and southern areas 

 more closely to each other than to the central portion. The 

 first two peculiarities of these terminal regions also seem to 

 indicate affinities with the island of Bonaire. 



The island of Aruba has, for peculiar forms, Neosululina 

 scopulorum, Thysanophora vanaUai, Cistulops raveni ariibana, 

 Brachypodella raveni aruhana and the form sinistrorsa, Micro- 

 ceramus honairensis aruhanus, Cerion uva ariihanum, two sub- 

 species of Tudora fossor, and the two South American forms, 

 Thysanophora crinita aruhana and Oxystyla maracaihensis 

 imitator. In general, the moUuscan fauna of this island is 

 most closely related to that of northern Curasao, with which 

 it possesses Tudora fossor in common; the subspecies of 

 Brachypodella raveni are also similar. However, Cerion uva 

 aruhanum appears most closely related with C. uva iiva from 

 central Curagao and Tudorata is similarly absent in both 

 regions. 



Bonaire and Klein-Bonaire together form the most distinct 

 of all of the areas, with the genus Stoastomops, the subgenus 

 Bonairea, Tudora aurantia, Neosubulina hai'terti (the most 

 remote of the three species), Brachypodella gihhonsi, Micro- 

 ceramus honairensis honairensis, Cerion uva honairensis, and 



