210 PROCEEDINGS OF THE ACADEMY OF [1895. 



This species belongs clearly to the group of ('. regina, lentiginomm, 

 etc., but it is a very thin shell, smooth like incana, with which it 

 has probably been confused in collections. 



Cerion (Maynardia) Maynardi P. and V. 



Shell large, strong, cylindrical, white or fleshy in the intervals 

 between strong, slightly curved ribs, separated by three times their 

 width on the cylindrical portion, which consists of 3 to 4 whorls; 

 those above forming a short cone on which the ribs are much closer. 

 Whorls 111, flat, the last ascending, becoming attenuated down- 

 ward, but with well rounded base, upon which the ribs are obsolete, 

 but replaced by fine costuhe. Umbilical rimation very deep, the 

 area below it rather wide, bounded by a spiral groove well within 

 the basal margin of umbilical tract. Aperture ovate-truncate, brown 

 within; parietal lamina very strong, thick but short; axial lamina 

 small, one whorl long. Peristome stout, broadly reflexed, its face 

 convexly thickened but not "duplicate;" broadly vaulted over the 

 umbilical region; parietal callus varying from thin to heavy. Alt. 

 35; diam. 15 mm.; apert. alt. 14; width 12 mm. Some specimens 

 fall under, some exceed these dimensions. Abaco, Bahamas. (Robert 

 Swift. ) Larger and coarser than G. abacoensis, and with far deeper 

 umbilical rimation and distant ribs. 



Cerion (Maynardia) yumaensis P. and V. 



Shell cylindrical, the lower three whorls of equal diameter, those above 

 tapering rapidly to form a short coue; white, mottled with fleshy-corneous 

 above, or having this color appear in sparse streaks, or in most or 

 all the intervals between the opaque white riblets throughout the 

 shell. Surface evenly, regularly and closely ribbed, the ribs sep- 

 arated by intervals slightly greater than their own width, about 29 

 on penult, whorl. Whorls 9?, the earlier two corneous, first one 

 smooth, next very minutely radially striate. Last whorl rounded 

 below. Umbilical chink much compressed, the tract below it semi- 

 lunar, defined by a groove. Aperture truncate-ovate, brown within; 

 parietal lamina small, short. Columella truncated obliquely; lip 

 expanded, not thickened; the parietal callus light. Alt, 24'. ; diam. 

 !'] mm. Yuma River, Hayti (Henry Prime) ; San Domingo (Gabb; 

 Salle). While superficially like C. striatellum, the different arma- 

 ture of the parietal wall at once distinguishes this species. The 

 parietal lamina is much reduced, almost absent in some specimens. 



