376 



MURICIDtE. 



Fig 642. 



Shell obliquely oval, narrowed at both ends, solid, coarse, spire 

 elevated and turreted, ash colored, composed of about six convex 



whorls, coarsely wrinkled by the 

 lines of growth ; lower whorl tur- 

 gid, and girdled by about ten broad, 

 elevated, rounded ribs or keels, of 

 a light reddish horn color ; they 

 are about equidistant, the poste- 

 rior one is the largest, and the suc- 

 cessive ones go on diminishing, 

 till, about the beak, they become 

 nearly extinct ; between the poste- 

 rior rib and the suture is a broad, 

 excavated shoulder, giving the 

 shell a turreted appearance ; the 

 two largest ribs revolve also on 

 all the upper whorls; the space 

 between the ribs is marked by fine 

 revolving lines ; aperture ovate ; 

 outer lip sharp, and modified by 

 the termination of the ribs ; inner 

 margin regularly arched, and thin- 

 ly spread with white enamel ; the pillar, at its lower third, twists 

 outwards to form a short, curved beak, and has, at this part, an im- 

 perfect umbilicus, bounded externally by a rough, obtuse spiral 

 ridge ; throat white, liaving shallow grooves of a chestnut color at 

 the margin, answering to the external ribs; operculum horny. 

 Length, three inches ; breadth, one and three fourths inches ; di- 

 vergence, sixty-eight degrees. 



Thrown up after violent storms on the shores of Massachusetts 

 Bay, and along more northerly coasts. It is seldom found with the 

 mouth entire, though it may contain the living animal ; showing 

 that it probably inhabits rocks in deep water. Eastport ( Cooper^ ; 

 fossil, Portland; Sable Island, &c. (Willis^. 



It resembles no other shell of the genus, unless, perhaps, it be 

 F. carinatus, which is a more ventricose shell, with fewer and nar- 

 rower ribs. But Kiener must be mistaken in regarding it as the F. 

 carinatus of Lamarck. There is no reason to suppose that his F. 

 carinatus was different from that of other authors, who give figures 

 varying widely from our shell. Kiener's figure is taken from a 

 small, slender specimen. It is still more like Purpura succincta, in 



F. decemcostatus. 



