CANALIFERA. MOLLUSCA. RANELLA. 297 



Strengthened by an entire rim of a dark, vitreous substance. 

 Length 7 inches, breadth 4 inches. 



Found in company with the preceding, but less abundant. It 

 is a shell belonging to a more southern latitude, and is found of 

 great size, and deep color, on the southern coast of the United 

 States. 



This is the largest convoluted shell on this Atlantic coast, and is rec- 

 ognised without difficulty. Still it exhibits great variety in appear- 

 ance, particularly in the length of the spinous tubercles. Sometimes 

 they are half an inch in length, and at others, mere traces of them are 

 all that is found on the larger volutions ; sometimes they are close at 

 the suture, even encroaching upon the whorl below; and at others, 

 they are removed to a considerable distance above it. In the old 

 shells the surface is a nearly uniform dead, ashy-gray color ; while 

 in the young, there are stripes at each stage of growth, and imperfect 

 bands of a violaceous-brown color. Southern specimens are more 

 luxuriant, with more brilliant colors, as might be expected from a 

 warmer chmate. 



Genus RANELLA, Lam. 



Shell oblong-oval, thick, nodulous, having a line of varices on 

 each side, formed at each half revolution ; aperture oval, terminat- 

 ing in a straight canal in front, and in a notch posteriorly ; lijj 

 thickened. 



Rane'lla cauda'ta. 



Shell rhomboidal, thick, cinereous brown, checkered with longi- 

 tudinal ribs and revolving lines, canal long and straight. 



Figure 204. 



State Coll., No. 3. Soc. Cab., No. 348. 



Ranella caudata. Say ; Journ. ^cad. Nat. Sc, ii. 236. Amer. Conch., pi. 48. 

 Adams ; Bost. Journ. Kat. Hist., ii. 269. 



Shell rhomboidal, solid, of a dark mahogany-color, obscured by 

 a substance like bluish-mould ; there are five angular whorls, trav- 

 ersed lengthwise by eleven elevated ribs, of which one at the left 

 side of the largest whorl, and the one bordering the aperture, are 

 38 



