M. glabratum.
M. crassilabrum.
M. cingulatum. The belted Monoceras.
Cylindrical, columella not smooth, but irregularly plaited or wrinkled, and the tooth does not extend within the interior of the whorls as in the other species, but appears affixed only to the edge of the lip; volutions flattened in their upper edges; transverse spiral brown bands.
6. Concholepas. One species.
Formerly considered a Patella, but distinct from it on account of having an operculum. It is particularly distinguished by having two teeth at the base of the right side.
Shell wide, rough, oval, spire very short, not projecting; aperture very large, oval, effuse, sloped anteriorly; the edges united; the right or external very thick, dentated; the two teeth which limit the slope are a little larger than the others; muscular impression visible, and almost in form of a horseshoe; operculum horny and rudimentary.
C. Peruvianus. The Peruvian Concholepas. Pl. [28], fig. 1.
The type of this genus; exterior dark brown, interior white.