MOLLUSCA OF PORTO RICO. 
403 
Nassa vibex Say. 
Nassa vibex Say, Journ. Acad. Nat. Sci. Phila., ir, p. 231, 1822. 
Nassa vibex Say, Am. Conch., pi. lvii, fig. 2. 
An exceedingly abundant, widespread, and variable species, and it is difficult to give a descrip- 
tion which will cover all the mutations. The shell varies from being quite obese to elevated; it has 
eleven or twelve longitudinal ribs; these are crossed by liner, revolving ridges or threads which make 
the summits of the longitudinal ribs somewhat nodulous. The shell is somewhat shouldered and is 
sometimes almost concave above the shoulder; below the suture there is an elevated, revolving ridge, 
which is sometimes cut into nodules by the longitudinal sculpture. The aperture is short, with a canal 
above, and is somewhat rhomboidal in shape. The outer lip is thickened and has from four to ten 
line within. The columellar callus spreads over the under side of the shell, and is sometimes thick 
and strong, and sometimes thin; it is slightly nodulous or wrinkled within the opening. The color 
varies from nearly white through ashy to dark brown or nearly black, and there is generally a light 
band at and above the periphery; the callus and lip are whitish or yellowish. 
Length, 10 to 15; diameter, 6 to 10 mm. 
San Juan, Porto Rico, a number of specimens; West Indian region, and the southeastern United 
States. 
Nassa ambigua Montagu. 
Buccinum ambiguum Montagu, Test. Brit., pi. ix, fig. 7, 1803. 
Another abundant and exceedingly variable species. ±t is a short, rather solid form, with gen- 
erally well-rounded or shouldered whorls, and a distinct, deep suture, which is sometimes canaliculate. 
There are thirteen or fourteen nearly straight, well-defined, rounded ribs, which are continuous from 
suture to suture, or to the base of the shell, and in addition there are distinct growth lines. These are 
crossed by numerous fine, revolving ridges, which are sometimes even and occasionally larger and 
smaller alternately. The aperture is small and almost round; the outer lip is thickened. Color white 
or yellowish, generally spotted or irregularly banded with brown. 
Length, 8 to 15; diameter, 5 to 9 mm. 
Aguadilla; Mayaguez, Porto Rico; Ensenada Honda; West Indian region; also (incorrectly?) 
reported from the west coasts of Africa and southern Europe. 
Nassa hotessieri d’Orbigny. 
Nassa hotessieri d’Orbigny, Moll. Cuba, ii, p. 142, atlas, pi. xxi, figs. 40-42, 1845. 
A number of young specimens and shells in bad condition were taken at Mayaguez and Ponce, 
and off Vieques, which are probably the above, but are hardly well enough preserved for positive 
identification. 
Family COLUMBELUDtE. 
Genus COLUMBELLA Lamarck, 1799. 
Shell oval, strombiform or somewhat elongated; aperture rather elongated, terminated by a short 
canal; outer lip thickened in the middle, generally toothed within; columella toothed or plicate; the 
base of the shell is narrowed. 
Subgenus Columbella s. s. 
Shell strombiform, with a rather short spire; aperture long, curved, narrow; outer lip thickened, 
incurved and swollen in the middle, toothed within, shouldered above; base notched; columella with 
several teeth or folds below; the lower part of the shell somewhat narrowed and drawn out; operculum 
unguiculate; nucleus apical. 
Columbella mercatoria (Linnseus) Lamarck. 
Voluta mercatoria'Jjiimxxis, Syst. Nat., ed. x, p. 730, 1758. 
Columbella mercatoria Lamarck, An. sans Vert., vil, p. 294, 1822. 
Columbella mercatoria Kiener, Coq. Viv., Columbella, p. 23, pi. v, fig. 1, 1841. 
This is one of the most abundant marine mollusks in the West Indian region. The shell is 
generally solid and somewhat cone-shaped; the spire is moderately elevated, the whorls are rounded 
