108 



POPULAR CONCHOLOGY. 



cirrhated posteriorly, grooved below, furnished in front 

 with a fold or mentum.* — About 100 species; also fossil. 



In these shells it is easy to distinguish the different 

 periods of growth, as the mouth is always bordered by a 

 thick lip, which is retained, and produces a band ; in the 

 adult shell these are very numerous, and from their ap- 

 pearance have given the name to the genus, Scalar ia or 

 Staircase. The seas of China and Japan produce the rare 

 species Scalaria pretiosa, for fine specimens of which, 3^ 

 inches in length, formerly the enormous price of one hun- 

 dred guineas has been given; they are now, however, 

 much more frequently met with, and may be obtained for 

 a few shillings. In this species the whorls only touch 

 each other at the thickened lip, and occasionally a speci- 

 men is found, in which they are perfectly separated. The 

 Scalaria communis inhabits our own coasts. 



Family 14. — JANTHIXA CEA. 



The animals have a small foot, not adapted for creeping, 

 behind which is fixed an apparatus, acting as a bladder, 

 by means of which the animal swims, floating on the top 

 of the water. The shell is thin, with a triangular mouth, 

 and perpendicular inner lip. Marine. 



Jantiiina. (Lam.) — Shell 

 sub-globular, whorls slightly an- 

 gulated ; right lip forming an 

 angle at the lower part of the 

 aperture with the columella, 

 which is produced so as to meet 

 it ; very fragile, thin, and of 

 a purple colour. Aiiimal, head 

 large, muzzle-shaped; two ten- 



Janthina communis. 



Forbes*s British Moll. 



