THE CYCLOPHORTD LAND M0LL1JSK.9 OF AMERICA 273 



Shell helicoid, moderately elevated and covered with an olive- 

 colored periostracum, which has irregular axial bands of brown. The 

 nucleus consists of 2 well-rounded, smooth turns. The postnuclear 

 whorls are well rounded, the last one falling very slightly below the 

 periphery at the peristome. There is an impressed groove a little 

 below the summit, which gives to the last half of the shell a slightly 

 channeled aspect at this place. The postnuclear whorls are marked 

 by very regular, retractively curved axial riblets, which grow less 

 regular and less strong toward the end of the last turn. In the groove 

 below the periphery there are also oblique scratches. Base moderately 

 broadly openly umbilicated, inflated, strongly rounded and marked 

 by the weak continuation of the axial ribs which extend over 

 the umbilical wall. Aperture circular; peristome thin; the outer 

 lip sharp ; the inner slightly thickened. The parietal wall is covered 

 by a moderately thick callus which renders the peritreme complete. 

 Operculum typically aperostomid, showing 6 whorls. 



The specimen figured is one of three, U.S.N.M. No. 307424, bearing 

 the label "New Grenada" (Colombia). It has 4.4 whorls and meas- 

 ures : Height, 16.2 mm. ; greater diameter, 22.4 mm. ; lesser diameter, 

 16.3 mm. Height of aperture, 10.8 mm. ; diameter, 11 mm. 



The following additional specimens are in the National collections : 

 No. 307405, two specimens from New Grenada; No. 307408, three 

 specimens from New Grenada. 



We have also figured a paratype of Baker's Poteria {Neocyclotus) 

 translucida santaguitensis on plate 30, figures 10-12, which agrees in 

 every way with the typical material. This specimen has 4.3 whorls 

 and measures : Height, 16.8 mm. ; greater diameter, 22.2 mm. ; lesser 

 diameter, 16.3 mm. Height of aperture, 10.2 mm. ; diameter, 11.2 mm. 



In the low spire this subspecies resembles most nearly A. (O.) 

 t. dunoonense, from which it can readily be distinguished by its larger 

 size. 



APEROSTOMA (CYCLOHmALGOA) TRANSLUCmUM DUNOONENSE, new subspecies 



Plate 30, Figxtbes 7-9 



Shell small, helicoid, moderately elevated, covered by an oliva- 

 ceous periostracum, through which the early whorls shine pinkish. 

 The nucleus consists of 2 well-rounded, smooth turns. The postnu- 

 clear whorls are strongly rounded, the last one appressed at the sum- 

 mit with a well-impressed groove immediately below the sum- 

 mit, which gives to the summit a corded appearance. The post- 

 nuclear whorls are marked by weak, retractively curved axial ribs, 

 which become obsolete on the last portion of the last turn. There are 

 a few oblique scratches in the depressed area below the summit. 



