212 



ly reflected at a right angle; there appears a very slight 

 indication of a groove or canal on the columella side, 

 not mentioned by Lamarck. Sowerby also observes, 

 that these shells possess a thin horny operculum. 



One of the most beautiful species of this genus, the 

 S. pretiosa (commonly called the Wentletrap), is ex- 

 tremely singular for its umbilicus, and the separation of 

 its spiral whorls, which appear like an attenuated tube 

 spirally evolved round a cone. The whorls are drawn 

 out, often quite separated from each other, or only slight, 

 ly connected together by the longitudinal ribs of the pre- 

 vious terminations of the aperture; and even these in 

 some examples do not touch, proving that they are not 

 essential to the support of the whorls; from which cir- 

 cumstance this genus may be considered nearly allied 

 to the G. Vermetus. There are many more species 

 known than those enumerated by Lamarck, as well as 

 many fossil species. See Sowerby 's Genera, No. 1 1. 

 Scalaria pretiosa Scalaria varicosa 



lamellosa communis 



coronata australis 



Scalaria raricosta. 

 [And three fossil species.] 



