MARINE MOLLUSCA OP THE UNITED STATES. 51 



Genus PLEUKOTOMELLA, Verrill. 

 Am. Journ. Science, v. 15. 1873. 

 1. P. PACKARDII, Verrill. 



Am. Journ. Science, v. 15. 1873. 



Shell thin, fragile, translucent, pale flesh-colored, moderately 

 stout, with an acute, somewhat turreted spire; whorls nine, the 

 apical whorls, for about two and a half turns, nearly smooth, regu- 

 lar, convex, chestnut-colored; below this the whorls are shoul- 

 dered, strongly convex in the middle, but with a smooth concave 

 band below the suture, corresponding to the posterior notch in the 

 outer lip; the whorls are crossed below the subsutural band by 

 about sixteen strong, prominent, rounded, somewhat oblique ribs, 

 most prominent on the middle of the whorl, but not angnlated ; 

 on the last whorl these ribs become very oblique below the middle, 

 and follow the curve of the edge of the lip, nearly filing out an- 

 teriorly ; the surface between the ribs is marked by faint lilies of 

 growth, and by fine, unequal, slightly raised revolving lines, which 

 pass over the ribs without interruption. They become more evi- 

 dent on the lower part of the last whorl, and are very faint on the 

 subsutural band, which is more decidedly marked by receding, 

 strongly curved lines of growth. The aperture is rather broad 

 above, elongated below, sub-oval, outer lip very thin, sharp, pro- 

 minent above, separated from the preceding whorl by a wide and 

 very deep sinus, extending back for about one-fifth of the circum- 

 ference of the whorl ; the anterior border of the lip is incurved 

 near the end and obliquely truncate, forming a short, straight 

 canal. Columella simple, nearly straight, its inner edge towards 

 the end sharp and obliquely excurved. 



Length 22, diam. 12 mill. 



Bay of Fundy, etc. 



Genus MANGELIA, Risso. 

 Moll. Eur. Merid. f. 101. 1826. 

 1. M. RUBELLA, Kurtz and Stimpson. 



Proc. Bost. Soc. Nat. Hist., iv. 115. 1851. 



Shell ovately fusiform, longitudinally costate, ribs elevated, 

 acute, spirally finely striate; whorls seven, angulate, the last 

 three-fourths the length of the shell; aperture narrow, one-half the 

 total length, lip thickened, scarcely sinuate; ribs wax-colored, 



