Oct. 1847.] 28i* 



Oliva Mississippiensis. 

 Subelliptical ; volutions six and a half; on the middle of the body whorl is a 

 slightly impressed revolving line. Length 1 1-10. Usual size f . Abundant. 



1. Mitra conquisita. 



Fusiform, slender, smooth and polished ; whorls eleven, slightly convex ; 

 penultimate whorl entire, except at the summit, where there are two impressed 

 lines forming a raised line between them ; the other whorls of the spire with 

 revolving lines, and towards the apex the intervening spaces transversely 

 wrinkled ; apex acute ; body whorl above the aperture, except the lines near 

 the suture, without striae ; inferiorly striated ; aperture narrow ; labium 

 3-plaited. Length 1 4-10. Very rare. 



2. M'tra Mississippiensis. 



Narrow-fusiform, with eight whorls, flattened at the sides and slightly sca- 

 lariform; whole surface with revolving unequal lines and longitudinal fine 

 wrinkles, obsolete on the lines but distinct on the intervening spaces ; aperture 

 more than half the length of the shell ; columella 3-plaited. Length If. Rare. 



In the young shell the strise are prominent over the whole surface, but in 

 adult specimens they become slightly impressed lines on the ventricose portion 

 of the body. 



3. Mitra cellulifera. 



Elevated-subfusiform ; slender ; whorls slightly turreted ; longitudinally 

 ribbed ; interstices with transverse impressed lines, resembling punctae or 

 cells ; beak produced ; labium 4-plaited, the second one from the top divided 

 by a slightly impressed line. Length |. Rare. 



4. Mitra staminea. 



Elliptical, whorls eight, slightly turreted, longitudinally ribbed ; ribs small, 

 numerous ; whorls with distinct impressed revolving lines ; body whorl ventri- 

 cose ; aperture about half the length of the shell ; pillar 4-plaited, the three 

 upper ones nearly equal. Length 4-10. 



5. Mitra Vicksburgensis. 



Elliptical, small; whorls slightly convex, with fine longitudinal ribs, obsolete 

 towards the suture inferiorly and wanting on the lower half of the body ; 

 suture profound ; aperture more than half the length of the shell ; pillar 

 4-plaited, the three upper ones nearly or quite equal in size. 



Distinguished from the preceding by wanting the revolving lines, and in 

 being wider in proportion to its length. 3-10. 



Caricella demissa. 

 Subfusiform ; whorls six, convex, one or two whorls near the apex distinctly 

 striated longitudinally, and with minute revolving lines ; upper part of the 

 whorls slightly concave ; apex papillated, first and second volutions smooth, 

 entire ; beak striated ; aperture about two-thirds the length of the shell ; colu- 

 mella 4-plaited. Length If* 



Scobinella. 



Shell subfusiform, with a deep angular sinus in the labrum as in Pleuro- 



