143 



the descriptions of both authors exclude an umbilical keel. 

 No. 3 has the same general form as the figure of C. subrug-o- 

 sum, but wants the umbilical keel. This species we are una- 

 ble to identify. The following nomenclature is proposed : 

 No. 1. Cyclostoma corrugatum ? Sowb. 



2. Cyclostoma jugosum Ad. sp. nov. 



3. Cyclostoma pallescens Ad. sp. nov. 

 5-14. Cyclostoma varians Ad. sp. nov. 

 15. Cyclostoma seminudum Ad. sp. nov. 

 16-18. Cyclostoma Jamaicense Chem. 

 19. Cyclostoma crassum Ad. sp. nov. 



' It will be seen that we have made much use of the oper- 

 culum. The differences of this part appear in this group to 

 be more constant and better defined than those of the shell. 

 They are evidently of value in distinguishing species and even 

 groups which are somewhat more comprehensive than species. 

 We would, however, with M. Petit and Mr. Redtield, stop far 

 short of assigning a generic value to the differences in the 

 opercula of the groups of Cyclostoma. 



No. 1. Shell reddish in the upper whorls ; in the lower whorls pale horn color 

 or dingy white ; with a brown epidermis : with deep transverse somewhat wrinkled 

 Btriaj on all the whorls ; foveately wrinkled, with shallow depressions ; with a dis- 

 tinct umbilical keel, and large curved pits exterior to the keel : spire well elevated: 

 whorls nearly five, flattened on the upper part, with a well impressed suture : aper- 

 ture suborbicular, quite effuse and pointed above : lip sinuate above, much ad- 

 vanced along the middle of the right side, naoderately thickened: umbilicus a 

 little more than half as wide as the aperture. Operculum with a much elevated 

 spiral lamella in nine whorls, which are much inflected curvately, the outer surface 

 being convex, like the sides of an inverted saucer. 



Mean divergence 120° ; height .55 inch ; greatest breadth .88 inch ; least 

 breadth .69 inch. 



No. 2. Shell white, with a light brown epidermis : with rather deep transverse 

 striae, which are very regular on the upper whorls, and very irregular on the last 

 whorl ; with deep wrinkles commencing near the end of the penult whorl, where 

 they are somewhat regular and oblique, as they are also on the lower side of the 

 last whorl, on the upper side of which they are irregular and knotty ; the umbilical 

 keel is obsolete : spire much depressed : whorls nearly five, well rounded, with a 



