136 NEW-YORK FAUNA — MOLLUSCA- 
PurruRa IMBRICATA. 
PLATE VIII. FIG, 173. 
Purpura imbricata. Lam. An. sans vertébres, Ed. prior, Vol. 7, p. 244. 
P. lapillus, var. Russet, Op. cit. Vol. 1, p, 70. Gouxp, Op. cit. p. 302. 
Description. Shell resembling the preceding in configuration, but more dilated, and not as 
solid : the spire more rapidly attenuated to the apex ; the revolving ribs are more numerous, 
and rather more distinct ; the ribs crossed by numerous waved imbricated scales, extending 
to the apex. Suture deep: whorls more convex; columella with a broad callus, and its base 
shorter and broader than in the preceding ; lip much rounded, expanded, and crenulated on 
the margin. 
Color. Greenish or greenish mixed with grey. 
Length, 0°7-— 1-0; of aperture, 0:5 -0°7,. 
Occurs with the preceding. Lamarck observes that it may be only a variety of the pre- 
ceding, but that it differs eminently by the imbricated scales, which render it rough to the 
touch. 
PurpPuRA BIZONALIS. 
PLATE VII. FIG, 174, 
Purpura bizonalis, Lamarck, An. sans vert. Ed. prior, Vol. 7, p. 249. 
P. lapillus, var. GouLD, Invertebrata of Mass. p. 303. 
Description. Shell rather smaller than the two preceding, solid: spire short, acute. Whorls 
four to five, with moderate revolving ribs on all except the apicial ones, which are smooth : 
body-whorl dilated ; lip not crenate; base of the columella short, emarginate at its junction 
with the lip: canal obsolete. ; 
Color. Chocolate-brown, with two revolving white bands, which are most evident on the 
body-whorl ; the upper band broadest. 
Length, 0°5 - 0°6. 
Occurs with the preceding, but is more rare. In old specimens, the ribs are strongly 
impressed by the incremental lines. 
(EXTRA-LIMITAL.) 
P. floridana. (Conrap, Ac. Sc. Vol. 7, p. 265, pl. 20, fig. 21.) Shell fusiform: whorls slightly 
concave above; spiral striz prominent, unequal. Whorls angular, with a series of tubercles on 
the angle; those of the spire longitudinally plicate; two terminal whorls smooth: lip thin, furrowed 
within on the margin. Color, varied white and brown; occasionally series of narrow pale stripes 
with brown spots. Florida, Alabama. 
