260 



XL. — Description of a new Land- SJiell from Trinidad, 



By R. J. Lechmere Guppy^ F.G.S. 



[Plate X. fig. 4.] 



Helicina lajnellosa, Guppy. PI. X. fig. 4. 



Shell orbicular, depressed, thin, somewhat diaphanous, liglit 

 fulvous ; sculptured with sharp spiral ridges, bearing thin, la- 

 mellar free edges, of which about four are on the upper side 

 of the whorls and from seven to ten on the scarcely convex 

 under surface, interlined with smaller ridges ; the interstices 

 between the ridges of the upper surface finely striate spirally, 

 of the lower surface shining, crossed by fine lines of growth ; 

 whorls 4^-5, keeled, with a lamellar free edge on the periphery. 

 Spire depressed, conoidal ; apex blunt, rather mamillary. 

 Aperture oblique, roundish, angulate by the carination of 

 the whorls. Peristome expanded and somewhat reflected, 

 bearing obsolete blunt points corresponding to the spiral 

 ridges : columella very short, simple : umbilicus covered by 

 a thin, granular, whitish callus. Operculum semiovate, con- 

 cave, thin, transparent, slightly tinted with fuscous, lined 

 with numerous concentric strise ; nucleus subcentral. 

 Height 2J millims., greatest diameter 4^ millims. 



The animal resembles that of Helicina barbata, a species found 

 in Trinidad. It is of a dark ashy-grey colour, passing into black 

 on the tw^o somewhat obtusely pointed tentacles, at the bases of 

 which are the small black eye-spots. The lingual dentition is 

 similar in general characters to that of the other species of He- 

 licina I have examined. The shell differs from all the typical 

 Helicince by being more depressed, and by the spiral ridges and 

 keel. The concentric striation of the operculum, which difixjrs 

 in texture from that of most HelicincSj is also an unusual cha- 

 racter; and many naturalists might be disposed to give the 

 present shell a new generic name. It may, indeed, be necessary 

 to mark its distinctness by a subgeneric title. I propose, there- 

 fore, for the shells characterized by the peculiarities 1 have just 

 noted the name of 



Perenna. 

 Operculum thin, suboval, concentrically striate ; nucleus sub- 

 central. Shell like Helicina, depressed; whorls lirate and 

 carinate. Animal like Helicina. 



Judging from the description of H. lirata, Pfeiffer (a native 

 of Yucatan), that species may possibly belong to the group now 

 characterized. 



I have found H. lamellosa only on one of the rocky islets 

 called the Cotoras, in the Gulf of Paria. 

 Port of Spain, Trinidad. 

 February 5, 1867. 



