36 Mr. Swainson on the Characters 
Shell thick, ovate, smooth, brown; spire contracted, suture mi- 
nutely crenated; outer lip thick, gibbous, smooth ; pillar 4-plaited. 
DuEscRiPTION. 
Length one inch, habit of M. crassata Sw. the basal volution is 
thick and rather ventricose; the spire is short and abruptly slen- 
der, having the upper margin of the whorls projecting beyond 
the suture, and minutely but regularly crenated ; the whorls are 
likewise crossed by a few remote strize, the inner margin of the lip 
is thickened, and gibbous, except at the aperture, which is white. 
The whole shell is of a uniform fulyous brown; inhabits the In- 
dian ocean, and is very rare. 
Mirra Acuminata. 
M. test crassa, levi, albente ; spird contracta, attenuat&é acumi- 
nata, apertura longiore; labii exterioris crassi margine inflexo, 
levis; columella 4-plicata. Shell thick, smooth, whitish; spire 
contracted, attenuated, acute, longer than the aperture; outer lip 
thick, the margin inflexed and smooth; pillar 4-plaited. 
On a cursory glance this shell (if in an imperfect state) might 
easily be mistaken for the last; when perfect, it is about an inch 
and a half long (the spire occupying considerably more than 
half this length) and is faintly striated. The spire when unin- 
jured is long, abruptly contracted, and terminates in an acute 
point. This part is so delicate, that in two specimens out of 
three which have come under my notice, it was wanting. The 
whorls are crossed by delicate indented strie, but are not in 
the least convex ; this character gives the suture an appearance of 
being channelled ; the outer lip is somewhat inflexed, the margin 
smooth, thick and slightly gibbous within the rim; the base is ob- 
tuse, and the whole shell white, covered with either a yellow or 
reddish brown epidermis. 
Inhabits the Mauritius.—A small though beautifully perfect spe- 
cimen is in the possession of Mr. Mawe. 
Mitra Canrinata. 
M. testa gracili, fusiformi, fusca, anfractibus medio carinatis, 
juxta suturam striatis, columella, 4-plicata. 
' Shell slender, fusiform, brown, whorls carinated in the middle, 
and striated transversely near the suture ; pillar 4-plaited. 
