SGALARIA 



Lmn, Hist, T^fat. des Aiiim. sans vert. VI. pt.2. p. 225. 



TESTA turrita, costis longitudinalibus elevatis, 

 subacutis; apertura rotundata, peritremate 

 continuo, marginato, reflexo: basi interna 

 obsolete subcanalieulata. Operculum tenue, 

 corneum, spirale. 



One of the most interesting of all Genem^ on account of 

 the extreme singularity of its numerous ribs, originating 

 in the circumstance of the border of its aperture being 

 turned backwards at fi-equent periods during its growth. 

 These ribs serve as one distinguishing mark between it 

 and all other turrited univalves, yet there are other 

 Genera which it might possibly be confounded with; these 

 are Pupa, and Cyclostoma; not that they are related to 

 it, but one of them, the Pupa, has even more numerous 

 ribs than the Scalaria, but they are not generally so dis- 

 tinct, and the shell may be distinguished by its cylindrical 

 shape: on the other hand, the Cydostomata never form 

 any ribs on their shell, their lip being only reflected at 

 the ultimate state of growth. 



Shell turrited, volutions gibbous, very distinct, some- 

 times quite separated, each succeeding one increasing in 

 size, and all more or less closely covered with longitudinal, 

 elevated, generally rather acute, and oblique ril3s ; these 

 ribs are sometimes thickened in such a manner as to 

 become distinctly varicose, but, on the contrary, in one 

 or two instances they are very indistinct, and scarcely 

 raised above the shell. The aperture is always nearly 

 tound, generally a little longer than it is broad, its edge 



