SCALARIA. 



GENERIC CHARACTER. 



Shell turrited ; volutions convex, gradually increasing 

 in size to the aperture, with numerous, elevated, longitu- 

 dinal ribs or varices; aperture nearly orbicular, slightly 

 longer than broad; peristome continuous, reflected: oper- 

 culum horny, spiral, thin. 



OBSERVATIONS. 



A genus of very pretty shells, known by the name of 

 Staircase shells by some collectors, and with respect to the 

 nature of which, naturalists formerly differed much. 

 Favanne and Gaulteri and othei"s, believed them to be 

 closely related to Serpula; and Rumphius placed them in 

 his Buccinum. Such as were known to Linne he refer- 

 red to Turbo, on account of the rotundity of the aperture. 

 In this respect they certainly also resemble Cyclostoma 

 and Pupa ; but the elevated ribs distinguish them from the 

 first, and the successive and regular increase in the size of 

 the volutions separate them from such species of the latter, 

 as have slight rib-like elevations. They seem also to aj)- 

 proach some species of the genus Rissoa in the character of 

 the ribs. 



The largest and most beautiful species, the scalaris, L. 

 (to which Lamarck has since given a different name) was 

 separated by Leach as the type of a new genus, to which 

 he gave the name of Aciona ; it is the '-Wcntletrap or royal 



