Mr Etheridge on a Small Naticiform Gasteropod. 163 



posed " buckie-fake," so that we now have much more satis- 

 factory material for placing this little Gasteropod on a firm 

 basis. The material thus to hand is briefly this: 



a. Specimens from the Shale in connection with the 

 Shelly Limestone at Eaw Camps Quarry, Collection 

 of the Geological Survey of Scotland — Mr Bennie. 

 h. Specimens from Shale of the Wardie Series at Drum- 

 sheugh, in the collection of Mr Gall. 



c. Specimens from the Shale of Craigkelly Quarry, 



obtained by Mr Bennie. 



d. A specimen and portions of others from decomposed 



Shelly Limestone at Piaw Camps Quarry — Mr 



Bennie. 

 Description of the Specimens. — When first described, these 

 little shells were, as before stated, referred to the genus 

 Littorina. After a lengthened and careful consideration of 

 them, and comparison with many genera both of recent and 

 extinct MoUusca, I have come to the conclusion they must be 

 referred to a separate genus, allied to Platyostoma (Conrad), a 

 genus met with in the Silurian and Devonian rocks of the 

 United States, and for which I propose the slightly dis- 

 tinctive name of PlcUyostomella. Eeasons for this step will 

 be given subsequently. I shall in the first place give the 

 generic and specific characters and observations thereon, and 

 afterwards pass on to a consideration of the generic affinities. 



Genus Platyostoma — Conrad. 



(Jour. Acad. Nat. Sciences, Philadelphia, viii., p, 275.) 



Sub-Genus Platyostomella, s-gen. 7wv. 



Char. — Shell dextral globoso-naticiform ; spire low ; body 

 whirl much expanded; aperture rotund-ovate, or transversely- 

 broad-oval; outer lip thickened and inner reflected; the 

 former rounded, with its upper portion almost at right angles 

 to the inner or coUumellar lip, which is remarkably straight, 

 direct, prominent, and pronounced, sometimes so far reflected 

 as to form a small callosity, but plain, never twisted or 

 plaited. Umbilicus probably present. Surface marked with 

 fine microscopic striae of growth. 



