3:2 AMERICAN MARINE CONCHOLOGY. 



Allied to B. Humphreysianum^ but differs in its plicated and 

 more convex whorls, deeper transverse sculpture and want of 

 color. It might be taken for a thin and delicate form of B. undu- 

 latum, but is easily distinguished by the number and straightness 

 of the longitudinal plications of the spire-whorls, the more nume- 

 rous and sharply-cut transverse ridges, and the wider mouth. 



5. B. Humphreysianum, Bennett. Fig. 47. 



Zool. Journ., London, i. 398, t. 22, upper figures. 1825. 

 Stimpson, Rev. of Bucciimms, Canad. Xat. 1865. 

 Buceinum ventricosum, Kiener, Iconog. Buc, iv. t. 3, f. 7. 1811. 



(not of Lamarck.) 

 Buceinum ciliatuia, Gould, Invert. Mass. 307, f. 209. 1841. 

 (not of Fabricius.) 



Shell rather below the medium size, veiy thin', translucent, pale- 

 brownish, with fulvous or reddish markings, sometimes obsolete. 

 Spire conic; whorls 7, somewhat flattened above and regularly 

 convex below, so as to be faintly shouldered above the middle. 

 They are neither plicated, carinated, nor angulated, and the sur- 

 face is much smoother than in most species of the genus.- The 

 primary ridges are to be distinguished from the secondaries only 

 at the obsolete angle or shoulder of the whorl, where there are 

 generally two or three small ridges on each side of the more pro- 

 minent ones and the corresponding sulcus. On the middle and 

 lower part of the body-whorl, where the transverse ridges are for 

 the most part equal in size and strength, and equal to the inter- 

 vening grooves, the latter are crossed by well-marked though mi- 

 croscopic lines of growth. The aperture is almost one-half the 

 length of the shell and about three-fifths as broad as long. The 

 outer lip is very little thickened and scarcely at all projecting 

 below, and it has no sinus at the middle. Periostraca ciliated. 



Length 37, diam. 20 mill. 



Gulf of St. Lawrence, northwards ; Northern Europe. 



It ma3 r be recognized by its thin structure, superior flattened 

 whorls, and the total absence of plications. 



Genus NASSA, Martini. 



Yerzeich. e. Ausserl. Samml. 1773. 



Shell ovate, ventricose ; body-whorl variously sculptured ; aper- 

 ture ovate, with a short, reflected, truncated anterior canal ; inner 

 lip smooth, often widely spread over with enamel, with a posterior 



