170 MITRID^. 



small ; spire acuminate, as long as the aperture ; inner lip exca- 

 vated, with two prominent plaits in the middle ; outer lip thin, 

 simple. M. alba, Pease. 



SWAINSONIA, H. and A. Adams. (Mitrella, Swains.) Oliviform, 

 smooth, polished, spire nearly as long as the aperture. M. fissu- 

 rata, Lam. (Iv, 37). 



SCABRICOLA, Swainson. Mitre-shaped or pyramidal, granulated 

 or scabrous. M. granatina, Lam. (Iv, 38). 



CANCiLLA, Swainson. Shell fusiform, slender ; whorls having 

 revolving elevated ridges, and no longitudinal ribs ; outer lip 

 thin, not dentate within. M. filosa, Lam. (Iv, 39). 



CHRYSAME, H. and A. Adams. Shell ovate, spire and aperture 

 usually about equal in length ; whorls encircled hy rounded 

 ribs ; inner lip with a few strong transverse plaits ; outer lip 

 with the margin crenate. M. coronata, Lam. (Iv, 40). 



STRIGATELLA, Swainson. (Mitreola, Swn.) Shell Columbelli- 

 form, smooth, uncolored or with brown longitudinal flames and 

 maculations. M. paupercula, Lam. (Iv, 41 \ 



ZIERLIANA, Gray. Ovate or Columbelliform, solid ; spire 

 short, acute, last whorl tumid at the hind-part ; columella with 

 a posterior callosity ; outer lip thick, flattened, lirate-dentate 

 within ; a sinus or short canal posteriorly. M. robusta, Reeve 

 (Iv, 42). 



FUSiMiTRA, Conrad. XJncharacterized. M. cellulifera^ Conrad 

 (Iv, 43). Oligocene ; Yicksburg, Miss. 



CONOMITRA, Conrad. XJncharacterized M. fusoides^ Lea 

 (Iv, 44). Eocene ; Claiborne, Ala. 



Thala, H. and A. Adams. 



Distr. — 12 sp. Polynesia, Philippines, Mauritius, Panama. 

 T. mirijica^ Reeve (Iv, 45). 



Small, narrowly fusiform, sculptured or smooth, last whorl 

 attenuated and recurved below; outer lip thickened, straight or 

 incurved in the middle, lirate internally, with a slight sinus at 

 the hind-part. Dentition unknown. 



MiTROiDEA, Pease. 



Syn. — Mauritia, A. Ad. Mutyca, H. and A. Adams. 



Distr. — 6 sp. Polynesia, Philippines, Mauritius. M. ancillides, 

 Swains. (Iv, 46). 



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 recurved at the base. Dentition similar to that 

 of Mitra. — Macdonald. 



Mitroidea is closely allied to Dibaphus, but the latter has a 

 shorter spire, and is without eolumellar folds. 



