50 AMERICAN MARINE CONCHOLOGY. 
ate, apex acute; aperture small, narrow, the outer lip crenated by 
the revolving striz ; 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. 851. 1834. 
Pleurotoma decussata, Couthouy. 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 striz, 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. vioLAcEA, 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 (Bur.). 
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. 
