178 CONTRIBUTIONS 
Observations. This species differs from the last in 
being broader, in having a shorter spire, in having one 
fold less, and in being thicker in the lip. 
WM. plicata. Plate 6. Fig. 189. 
Description. Shell ovate, longitudinally folded above ; 
substance of the shell rather thick ; spire short, rounded 
at the apex; whorls three, flattened above; columella 
with six folds; mouth narrow, curved ; outer lip thick, 
finely crenulate within. 
Length 5-20ths, Breadth 3-20ths, of an inch. 
Observations. Differs from all the species herein de- 
scribed, in having longitudinal folds, which are placed on 
the superior part of the whorls. 
JM. semen. Plate 6. Fig. 190. 
Description. Shell ovato-elliptical, polished ; substance 
of the shell rather thick ; spire very short and rounded at 
the apex ; whorls three, flattened above ; columella with 
six folds; mouth narrow, curved; outer lip somewhat 
thick and very minutely crenulate within. 
Length 5-20ths, Breadth 3-20ths, of an inch. 
Observations. This species seems most analagous to the 
last described, but is without its exterior folds, and is more 
elliptical. 
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