178 



tinged with green towards the umbones, broadly radiated with very 

 pale ferruginous and dusky purplish, with numerous dots and ab- 

 breviated lines of purple-black: anterior margin with transverse, 

 oblique, purple black lines : posterior margin pale ferruginous : 

 lunule dusky, bounded by an impressed line : umbones not very 

 prominent : hinge margin nearly rectilinear, terminated anteriorly 

 by an obtuse angle ; in this part the edge of the left valve laps a 

 little over and conceals the corresponding part of the edge of the 

 right valve : ligament deeply seated : posterior margin rounded : 

 lunule impressed, distinct by an impressed line : within, very 

 broadly margined with violaceous ; margin crenated : intermediate 

 tooth emarginated at tip : anterior tooth of the left valve also 

 emarginated. 



Obs. This beautiful species was presented to me by the late Mr. 

 Stephen Elliott of Charleston, S. Carolina, as an inhabitant of the 

 west coast of Mexico. The colored lines on the anterior part of 

 the shell, are somewhat like those of V. geographica, Gmel., but 

 these lines have a bluish shade forwards, are more regular than in 

 the figure of that species in the Encycl. Meth., and as a species it 

 widely distinct. 



I have an indistinct recollection of a figure resembling this spe- 

 cies, but I cannot recall the work, for the purpose of comparing 

 the characters. PI. 26. 



ScALARiA. — Shell turrited; volutions convex, gradually in- 

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

 dinal ribs or varices ; aperture nearly orbicular, slightly longer than 

 broad; peristome continuous, reflected; operculum horny, spiral, 

 thin. 



Ohs. 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 difiered much. Favanne and Gaul- 

 teri and others, believed them to be closely related to Serpula; and 

 Rumphius placed them in his Buccinwn. Such as were known to 

 Linne he referred 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 approach some species of the 

 genus Rissoa in the character of the ribs. 



