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careful to subjoin to the generic names that are here adopted^ ab- 
breviations of the author’s names, who formed them respectively, 
or whose generic definitions I have followed. 
Type and Class MOLLUSCA aASTEROPODA. 
Patella amcena. — Shell oblong-oval, whitish reticulated vfith 
reddish-brown, and sculptured with numerous minute concentric 
wrinkles and close set radii ; margin entire ; apex placed behind the 
middle, and pointing backwards. 
Coast of New England States. 
Length of a small specimen, seven-twentieths, breadth one-fifth 
of an inch. Breadth of a larger one three-tenths, nearly. My cabinet. 
It may be readily distinguished in general by the beautiful 
reticulated disposition of the rufous color, inclosing small irregularl}" 
oval, white, or yellowish-white spots. They sometimes, however, 
are of a uniform greenish or brownish color. Several specimens 
of this species were communicated to me by Mr. Aaron Stone, who 
found them on the coast of Maine. 
Eissurella alternata. — Shell oblong-ovate, moderately 
thick, cinereous or dusky, with equal concentrated lines, crossed 
by alternately larger and smaller radii, all which are equable or not 
dilated in any part ; vertex placed nearer the smaller end ; perfora- 
tion oblique, oblong and a little contracted in the middle 3 within 
white ; margin simply crenate ; apex with an indented transverse 
line at the larger end of the perforation. 
Length four-fifths of an inch. Breadth three-fifths. Height 
more than two-fifths. Inhabits the coast of the United States. 
Cabinet of the Academy, and Philadelphia Museum. 
Bears a general resemblance in its sculpture to F. grseca, but the 
radii are not dilated at the points where they are crossed by the 
concentric lines. I have specimens from the coast of Maryland 
that measure one inch and a half in length. 
Crepidula eornicata ? var. — Shell transversely wrinkled, 
varying in convexity, with obsolete longitudinal, undulated, rufous 
lines one side more oblique than the other ; apex excurved, a little 
prominent, but not separated from the body of the shell, and gene- 
rally united with the margin of the aperture ; aperture suboval ; 
diaphragm a little concave, occupying at least half of the length, 
edge generally declivate. 
8 
