170 MITRIDA. 
small; spire acuminate, as long as the aperture; inner lip exca- 
vated, with two prominent plaits in the middle; outer lip thin, 
simple. JM. alba, Pease. 
swarinsoniA, H.and A. Adams. (Mitrella, Swains.) Oliviform, 
smooth, polished, spire nearly as long asthe aperture. MW. jfissu- 
rata, Lam. (lv, 37). 
SCABRICOLA, Swainson. Mitre-shaped or pyramidal, granulated 
or scabrous. M. granatina, Lam. (lv, 38). 
CANCILLA, Swainson. Shell fusiform, slender; whorls having 
revolving elevated ridges, and no longitudinal ribs; outer lip 
thin, not dentate within. MM. filosa, Lam. (lv, 39). 
CHRYSAME, H.and A. Adams. Shell ovate, spire and aperture 
usually about equal in length; whorls encircled by rounded 
ribs; inner lip with a few strong transverse plaits ; outer lip 
with the margin crenate. MM. coronata, Lam. (lv, 40). 
STRIGATELLA, Swainson. (Mitreola, Swn.) Shell Columbelli- 
form, smooth, uncolored or with brown longitudinal flames and 
maculations. MM. paupercula, Lam. (lv, 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; asinus or short canal posteriorly. J. robusta, Reeve 
lv, 42). 
FUSIMITRA, Conrad. Uncharacterized. M. cellulifera, Conrad 
(lv, 43). Oligocene ; Vicksburg, Miss. 
CONOMITRA, Conrad. Uncharacterized. MM. fusoides, Lea 
(lv, 44). Hocene; Claiborne, Ala. 
THata, H. and A. Adams. 
Distr.—12 sp. Polynesia, Philippines, Mauritius, Panama. 
T. mirifica, Reeve (lv, 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. 
Mirro1DEA, Pease. 
Syn.—Mauritia, A. Ad. Mutyea, H. and A. Adams. 
Distr.—6 sp. Polynesia, Philippines, Mauritius. J. ancillides, 
Swains. (lv, 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.—MacpDonaLp. 
Mitroidea is closely allied to Dibaphus, but the latter has a 
shorter spire, and is without columellar folds. 
