28 Unizcrsity of Michigan 



CYCLOPHORIDAE 

 Aperostomatinae 



The synonymy of the major groups of this subfamily has 

 been reviewed in an earHer paper.* Of the South American 

 genera, Buckleyia appears to extend only as far north as south- 

 ern Colombia. Besides the numerous species of Amphicyclotus 

 from Central America and northwestern South America, A. 

 caycnnensis (Shuttleworth, 1852), from Cayenne, Guiana, ap- 

 pears to belong to the same group as the species from the Les- 

 ser Antilles. With the exception of the doubtful Cydostoma 

 psilomitiim (see below), the subgenus Xeocyclotus, of the gen- 

 us Poteria, is the only group that has been reported from Ven- 

 ezuela. 



A brief synopsis of the mainland species of Xeocyclotus will 

 \ie presented. All of the species included here, with the ex- 

 ception of P. corpulenta (Smith), have been figured. The 

 most recent bibliographies are found in Kobelt (1902, Thier- 

 reich) and Kobelt- Schwanheim (1912, Conch. Cab.). In the 

 following synopsis, those species preceded by an exclamation 

 point ( !) are not included in either of these monographs, but 

 are figured by their authors. Those preceded by an asterisk 

 (*) are not in the Conch. Cab. 



Although Pfeiflfer (Conch. Cab.) describes the operculum 

 as calcareous, I \tvy much doubt the position of Cyclostoma 

 promimda "Ferussac" Orbigny (1835) {-^Cyclostoma bra- 

 silicuse Sowerby, 184 — , +C. planorbulum Sowerby, 1842), 

 as a member of the subgenus Neocyclotus. The apical whorls 

 are those of the Lesser Antillean group of Amphicyclotus, 

 while the solute last whorl is quite distinctive, although it oc- 



"Aperostomatinae," The Nautilus, xxxv, July, 1922. 



