284 [Oct. 1847. 



revolving impressed lines, commencing near the upper angle of the aperture ; 

 volution contiguous to the apex, papillated ; labium striated ; aperture rather 

 more than half the length of the shell ; beak perfectly straight. Length \\. 

 Rare. 



This shell may perhaps appertain to Brachytoma, Swainson. 



2. Pleurotoma Mississippiensis, 

 Turreted ; volutions eight, concave above and plain below, with longitudinal 

 distant rounded ribs ; body whorl with revolving lines, commencing in a line 

 with the summit of the aperture ; beak short, a little curved. Length f . 



3. Pleurotoma servata. 



Fusiform ; whorls ten, with rounded longitudinal ribs and prominent strong 

 revolving lines, a fine intermediate line on the body whorl ; volutions concave 

 above, with a carinated revolving line below the suture ; beak narrow, elongated, 

 slightly bent, acuminate ; aperture and canal rather more than half the length 

 of the shell. Length 9-10. 



4. Pleurotoma congesta. 



Short-fusiform, volutions nine or ten, with revolving raised lines and longi- 

 tudinal wrinkles; spire conical-acute; whorls slightly contracted in the middle, 

 with longitudinal curved irregular stria?, interrupted in the middle of each 

 whorl; aperture half as long as the shell ; beaks slightly twisted. Length 1-1 0th. 

 Very abundant. 



It approaches the genus Brachytoma, Swainson. 



5. Pleurotoma cristata. 



Fusiform, whorls ten, angulated in the middle, except the two from the 

 apex, and with a reflected finely dentate carina ; revolving lines distinct, finely 

 crenulated ; spire scalariform; from the upper end of the aperture runs a promi- 

 nent revolving line, much larger than the others : lines on the body whorl 

 below the angle minutely granulated; beak narrow, produced. Length f. Rare. 



6. Pleurotoma tantula. 



Slender ; volutions nine, convex, with longitudinal rounded, slightly curved 

 ribs ; spire elevated and acute ; suture margined by an indistinct raised line ; 

 beak short, narrow. Length 4-10. Rare. 



A member of subgenus Clavatula, Lam. 



7. Pleurotoma tenella. 



Fusiform ; volutions nine, whorls slightly contracted above, with longitudinal 

 prominent curved lines, and a prominent revolving line near and below the su- 

 ture ; between this and the suture an impressed line ; body whorl with strong 

 prominent revolving lines, commencing in a line with the upper end of the 

 aperture, and sometimes alternated in size ; ribs frequently obsolete on the 

 body whorl, and terminating at the striated space; beak narrow, somewhat 

 produced. Length 8-10. 



It probably belongs to Swainson's genus Clavicantha. 



8. Pleurotoma cochlearis. 



Subfusiform, with elevated revolving lines, alternated with fine lines, the in- 



