70 BULLETIiN 181, UNITE© SfTATEiS NIATIONIAIL MUSEUM 



the outer edge, leaving a tear-drop-shaped space separating them 

 basally. This lamella bears strong oblique threads. The dorsal 

 chondroid plate is projected and upward turned at the outer edge 

 of the last whorl to the height of the calcareous lamella or slightly 

 above it. The upturned edge is slightly fimbriated. 



Type: Cyclostoina dubiosum C. B. Adams^ Cyclovendrey)sia 

 dubiosa (C. B. Adams). 



We have been unable so far to find a male of this species. The 

 radula has the formula 3:3:3:3, and the jaw lacks distinct median 

 projections. 



CYCLOVENDREYSIA DUBIOSA (C. B. Adams) 



Plate 12, Figukes 4-6 



1851. Cyclostoma dubiosum C. B. Adams, Ann. Lye. Nat. Hist. New York, vol. 5, 

 p. 81. 



Shell lenticular, very widely openly umbilicated, covered with a 

 brownish wax-colored periostracum. There is one nuclear turn, 

 which is rounded and smooth. Postnuclear whorls inflated, strongly 

 rounded, separated by a profoundly impressed suture and marked 

 by slender, almost vertical, closely placed, hairlike axial riblets, which 

 are a little more distantly spaced on the first turn than on the re- 

 maining turns. Periphery strongly rounded. Base very broadly 

 openly umbilicated, well rounded, marked like the spire, which is 

 also the sculpture of the umbilical wall. In cross section the whorls 

 are circular. Aperture slightly oblique, circular; peristome simple. 

 Operculum described in our generic diagnosis. 



The specimen figured, U.S.N.M. No. 356120, is one of several col- 

 lected by John B. Henderson at Ipswich, St. Elizabeth Parish, 

 Jamaica. It has 4.5 whorls and measures: Height, 6.5 mm.; greater 

 diameter, 14.5 mm. ; lesser diameter, 11.0 mm. 



The United States National Museum contains 22 lots, and in addi- 

 tion to this I have seen two lots from the C. B. Adams collection 

 and four from the Academy of Natural Sciences of Philadelphia. 



The material before me enables me to say that the species ranges 

 from the northwestern corner of St. Elizabeth Parish northward to 

 Montego Bay, St. James Parish, through Trelawny to Browns 

 Town, St. Ann Parish. Throughout this range it shows no differen- 

 tiation into races. 



While the shell in general form resembles Cyclojamaicia suturalis 

 (Sowerby) and C. hondi (Vanatta), its entirely different operculum 

 and absence of sutural keel remove it at once from that complex. 



