MITRA. 109 



ZIERLIANA, Gray. Ovate or C'olumbellifoi-m, solid; spire short, acute, 

 last whorl tumid at the hind part; columella with a posterior callosity; 

 outer lip thick, llattencd, lirate-dentate within; a sinus or short canal 

 posteriorly. Dentition, PI. 2, fig. 13. 



MITKOIDEA, Pease. Shell mitriform, smooth, spire acuminated ; 

 aperture narrow, linear; columella with numerous, small oblique plaits, 

 narrowed and turned to the- left at the base; outer lip thickened, 

 peculiarly truncated and recui-ved at the base. Dentition similar to 

 that of Mitra.— Macdonald. 



DIBAPHUS, Philippi. Subcylindrical, covered with a thin epidermis, 

 transvei'sely sculptured; spire acute; aperture narrow, linear; columella 

 without plaits, narrowed and turned to the left at base; outer \ip 

 thickened, rectilinear, abruptly truncated and recurved at the base. 

 Dentition unknown. The unarmed columella is the principal and 

 perhaps insufficient distinction for this genus from Mitroidea. 



TURRICULA, Klein. Shell elongated, turreted, longitudinally plicately 

 ribbed; spii-e acuminated; aperture narrow; columella with numerous 

 plaits; outer lip internally htriated. Dentition, PI. 2, fg. 13. 



CYLINDRA, Schumacher. Shell oliviform, subcylindrical: spire conical; 

 aperture linear; columella straight, with several oblique anterior 

 plaits; outer lip thickened, smooth within. Dentition, PI. 2, fig. 15. 



IMBRICARIA, Schumacher. Shell coniform, often covered with an 

 epidermis; spire depressed conical, apex mucronate; aperture linear; 

 columella straight, with numerous transverse imbricated plaits in the 

 middle; outer lip thickened. 



Fossil Genera. 

 LAPPARIA, Conrad. Uncharacterized. 



L. DUMOSA, Conrad. PI. 3, fig. 43. Eocene, Jackson, Miss. 



FUSIMITRA, Conrad. Uncharacterized. 



F. CELLOLiFERA, Conrad. PI. 3, fig. 40. Oligocene, Vicksburg, Miss. 

 CONOMITRA, Conrad. Uncharacterized. 



C. FusoiDES, Lea. PI. 3, fig. 41. Eocene, Claiborne, Ala. 



^ (Jenus MITRA, Laiu. 



The animal of Mitra has in general a verj^ short foot, straight 

 and continuous from side to side in some species, but in others 

 notched and produced, with a thickened anterior margin. It is 

 commonl}^ narrow and rounded, or acuminated posteriori}', and 

 it often bears a very small semitransparent horny operculum, in 



