THE CYCIiOPHORID LAJSTD MOLLUSKSI OF AOVEEKIlOA 69 



CYCLOJAMAICIA SUTURALIS (Sowerby) 



Plate 12, FiGtrsEs 10-12 



1843. Cyclostoma suturale Sowekby, Proc. Zool. Soc. London, vol. 11, p. 29. 

 1843. Cyclostoma suturale G. B. Soweeby, Thesaurus Conchylionim, vol. 1, 

 p. 91, pi. 23, figs. 1-2. 



Shell lenticular, very widely umbilicated, covered with an oliva- 

 ceous, wax-colored periostracum. Nuclear whorls about 1, well 

 rounded, smooth. Postnuclear whorls strongly rounded, the first one 

 with a normal suture, the rest with a decidedly elevated keel, sep- 

 arated from the preceding turn by a very deeply channeled suture. 

 The keel in fact is a backward reflection of succeeding stages of 

 the edge of the peristome, near the posterior angle of the aperture, 

 where there exists a sinus, which forms a notch in the peristome, 

 which serves as a breathing pore when the operculum closes the 

 aperture. The postnuclear whorls are marked by very closely spaced, 

 hairlike, sublamellar axial riblets. These in crossing the keel at the 

 summit become decidedly backward bent. Periphery well rounded. 

 Base well rounded, marked like the spire. Aperture circular, except- 

 ing the sinus at the posterior angle referred to above. Peristome 

 simple. Operculum as described in the generic diagnosis. 



The specimen described and figured, U.S.N.M. No. 535685, is one 

 of four collected by Dr. H. Burrington Baker at his station J22, 

 that is, the hill north of Rotten Gut, Manchester Parish, Jamaica. 

 It has 4.5 whorls and measures : Height, 7.0 mm. ; greater diameter, 

 14.4 mm. ; lesser diameter, 10.6 mm. 



We have 23 additional lots of this species, all of which come from 

 the edge of the Cockpit country, from the northeastern part of 

 St. Elizabeth to the northwestern part of IManchester Parish and 

 the extreme southern part of Trelawny Parish. All this material 

 comes from within a radius of 6 miles. 



This species is easily distinguished from Cyclojamaicia hondi 

 (Vanatta) by its much narrower channeled suture between the sum- 

 mit and the keel. Furthermore, the keel at the summit in suturaXis 

 is acute, while in C. hondi it is rounded. 



Sowerby, in describing this species, said that G. C. Bainbridge, 

 of Liverpool, had received a few specimens many years ago from 

 the woods of Demerara. This is undoubtedly a mistake, for nothing 

 like it has ever been reported from the mainland. 



CYCLOVENDREYSIA, new genus 



Small, planorboid, widely umbilicated aperostomids, the whorls 

 of which are circular in cross section, the sculpture consisting of 

 incremental threads only. Operculum with a multispiral calcareous 

 lamella, which is outward reflected to touch the succeeding turn at 



