50 AMERICAN MARINE CONCHOLOQY. 



ate, apex acute ; aperture small, narrow, the outer lip creuated by 

 the revolving stria; ; white, or tinged with purple. 

 Length 9, diam. 4 mill. 



Casco Bay, Maine (rare), northwards. 



5. B. trevelyana, Turton. Fig. 84. 



(Pleurotoma.) Mag. Nat. Hist., vii. 351. 1834. 

 Pleurotoma decussata, Coutkouy. Bost. Journ. Nat. Hist., ii. 183, t. 4, f. 8. 

 1839. 

 Shell ovate-fusiform ; whorls five or six, convex, with twenty- 

 five or more minute longitudinal ribs or folds, and numerous fine 

 revolving striae, suture well marked ; body-whorl two-thirds the 

 length of the shell, the ribs becoming obsolete on its lower part ; 

 aperture narrow, oval, one-half the length of the shell; white or 

 flesh color. 



Length 10, diam. 5 mill. 



Massachusetts, northward. 



6. B. yiolacea, Mighels and Adams. Fig. 85. 



(Pleurotoma.) Bost. Journ. Nat. Hist., iv. 51, t. 4, f. 21. 1842. 

 Defrancia Beckii. Moll. 1842. (Jeffreys.) 



Shell ovate-fusiform ; whorls six, convex, longitudinally slightly 

 plicated, spirally finely striate ; the body-whorl slightly shouldered 

 and folds becoming obsolete at its middle, spire-whorls with a 

 median revolving carina ; aperture small and narrow, canal very 

 short and wide. Dark purple, under a pale-brown epidermis. 

 Length 7.5, diam. 3 mill. 



Massachusetts Bay, northward (Eur.). 



7. B. undatella, Gould. 



Proc. Bost. Soc. Nat. Hist., viii. 281. 1862. 



Shell ovately rhomboidal, transparent, white, shining, slightly 

 spirally striate ; apex mamillate ; whorls four tabulate (angulately 

 rounded) with a subsutural impressed line and about eight opaque 

 longitudinal undulations ; aperture about half the length of the 

 shell. 



Length 3, diam. 1.5 mill. 



The transparency and mamillated tip of the minute shell renders 

 it plausible that it may be the young of some larger species. 

 Dredged in 400 fathoms. 



Coast of Georgia. 



