179 



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

 which Lamarck has siuce 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 " Wentletrap or royal staircase shell" of the 

 English collectors, and Scalata of the French, belonging to the 

 subdivision of this genxis, which is distinguished by having the 

 volutions separated, or only touching each other by the projecting 

 ribs. This shell was very highly valued, and Leach mentions ;i 

 specimen '' which was purchased at a sale for twenty pounds ; but 

 it is now (1815) estimated as worth double that sum." Cubieres 

 says that in his time, a fine specimen of four French inches long 

 by three inches at base, was worth six thousand livres. To the 

 same division of the genus, it is said, about twelve species are re- 

 ferred. 



Blainville, after Plancus and Muller, describes the animal to be 

 spiral, with a short oval foot inserted under the neck ; two tenta- 

 cula, with filiform termination, supporting the eyes at the extremity 

 of the inflated part ; a proboscis ? ; a long canal at the anterior right 

 margin of the respiratory cavity ; sexes separate. 



They are all inhabitants of the sea. Lamarck has characterized 

 seven recent and five fossil species ; but Defrauce enumerates 

 twelve fossil species. 



SCALARIA CLATHRUS, Lin. — Turbo clathrus, Linn. Gmel &c. 



Scalaria communis, Lam,. 



Scalaria clathrus, Auct. * 



Desc. Variety c. Shell conic, turreted, imperforate, white, im- 

 maculate : whorls from six to eleven, touching each other only by 

 the ribs, but with a very narrow interval : ribs nine to each volu- 

 tion, prominent, simple, a little oblique, somewhat recurved and 

 with a more or less obvious, obtuse angle or shoulder above near 

 the suture : aperture oval-orbicular ; base a little angulated : labium 

 distinct. 



Length from three-fifths to nearly nine-tenths of an inch. 



Ohs. Inasmuch as the European specimens of clathrus in my 

 collection are almost all colored, spotted or banded and destitute 

 of any obvious angle or shoulder on the ribs near the suture, and 

 the suture is somewhat more contracted, I was led to describe 

 this as a distinct species under the name of angulata ; but as the 

 clathrus is often, and perhaps usually, destitute of color, and our 



