288 INVERTEBRATA OF MASSACHUSETTS. 



ternally by a rough, obtuse, spiral ridge ; throat white, having 

 shallow grooves of a chestnut-color at the margin, answering to 

 the external ribs ; operculum horny. Length 3 inches, breadth 

 1| inch, divergence 68°. 



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 ; show- 

 ing that it probably inhabits rocks in deep water. 



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

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

 er ribs. But Kiener must be mistaken in regarding it as the F. cari- 

 natus of Lamarck. There is no reason to suppose that his F. cari- 

 natus was different from that of other authors, who give figures vary- 

 ing widely from our shell. Kiener's figure is taken from a small, 

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

 aspect. It is subject to but little variation ; the most important one is, 

 that a third rib is found upon one or more of the upper whorls. 



FUSUS SCALARIFORMIS. 



Shell fusiform^ white or reddish-broicn., with fifteen or twenty 

 longitudinal^ compressed ribs ; aperture of the length of the spire. 



Figure 203. 



State Coll., No. 164. Soc. Cab., No. 2356. 



Fusus scalariformis, Gould; Silliman's Journ., xxxviii. VJ7. 



Shell tapering at both extremities, reddish-brown in the young- 

 er stages, white when old, whorls seven, turgid, covered at close 

 intervals with fifteen to twenty compressed, white ribs, or arching 

 plates, laying over each other like tiles ; they are generally a little 

 flexuous, the edges sharp and jagged when young, and more 

 erect, smooth, and blunt on old specimens ; they are usually some- 

 what more elevated at the posterior part of the whorls, so as to 

 produce an angular, or coronated appearance ; the interstices, in 

 adult shells, are smooth, somewhat wrinkled at the sutures, with 

 numerous faint, revolving lines, which are not visible on younger 

 shells ; aperture half the length of the shell, produced into a 

 moderately long, slightly recurved beak, irregularly wrinkled by 



