MOLLUSC A OF PORTO RIOO. 
443 
Subgenus Omphalius. 
Chlorostoma scalare Anton. 
Trochus sealaris Anton (in) Philippi, Abbild. und Besohr., i, Trochus, pi. iv, tig. 11, 1844. 
Shell trochiform, with pointed summit; whorls seven, rounded or sometimes slightly shouldered, 
the last subcarinate on the periphery, sculptured with close, revolving threads which are usually 
subnodulous; some of these threads are stronger than others and cause the shell sometimes to be 
slightly angular on the upper part of the whorls; aperture oblique; lip thickened; umbilicus wide, 
with two or three strong, revolving ribs within; columella concave, ending in two or more teeth 
below. Color grayish or greenish gray, with mottlings of darker color. 
Height, 16; diameter, 20 mm. 
Playa de Ponce; Puerto Real; Guanica; Arroyo, Porto Rico; Caballo Blanco Reef, Vieques; 
Ensenada Honda, Culebra. 
Chlorostoma fasciatum Born. 
Trochus fcisciatus Born, Mus. Caes. Vind., p. 331, pi. xn, figs. 3, 4, 1780. 
Shell depressed conical, with a somewhat rounded spire and rather blunt apex; whorls rounded 
below, and flattened or faintly concave above, smooth, with the exception of very faint, wavy, revolving 
lines and equally faint growth lines; lip thick, sometimes double and faintly ridged within; umbilicus 
moderate, with one strong ridge within. The shell shows a great variety of coloring; the ground may 
be yellowish red or various shades of brown, with tine, revolving rows of small, angular white spots. 
There is generally a light band on the rounded periphery, and there may be blotches or irregular, 
radiating, whitish flames above. 
Height, 12; diameter, 15 mm. 
Playa de Ponce; Guanica; Puerto Real; Arroyo, Porto Rico; Ensenada Honda, Culebra. 
Chlorostoma excavatum Lamarck. 
Trochus excavatus Lamarck, An. sans Vert., vii, p. 29, 1822. 
Chlorostoma excavatum Pilsbry, Man., xn, p. 187, pi. i.xiii, figs. 3-5, 1899. 
Shell trochoidal, sides slightly convex; whorls but little rounded, the last strongly but not sharply 
carinate at base, sculptured with wide, low, revolving ribs; aperture very oblique; outer lip not much 
thickened; columella sinuous, scarcely swollen ; umbilicus moderate, half surrounded with sickle-shaped 
callus; base generally concave, with strongly marked, revolving lira;. The apex is usually eroded, the 
rest of the shell above is grayish or pinkish, with irregular, subradial, broken, brown markings. 
Height, 10; diameter, 15 mm. 
Aguadilla; Hucares, Porto Rico; Ensenada Honda, Culebra. 
The upper half of the shell is generally much eroded. 
Chlorostoma maculostriatum C. B. Adams. 
Monodonta maculostriata 0. B. Adams, Proc. Bost. Soc. Nat. Hist., v, p. 6, 1845. 
Chlorostoma maculostriatvrn Pilsbry, Man., xi, p. 184, pi. xxiv, figs. 88, 89, 1889, 
Shell umbilicate, low conical; whorls slightly convex, the last feebly angulate at the base; the 
surface is covered with fine, but distinct, revolving strife; base concave around the umbilicus; aperture 
subquadrate; columella with a callus above and two rather strong teeth below. Color dark green, 
olivaceous or brownish, more or less dotted with white, sometimes flamulate with white; a light tract 
at the umbilicus is dotted with brown. 
Height, 9; diameter, 10 mm. 
Hucares; Arroyo, Porto Rico, one young shell. 
Genus LIVONA Gray, 1842. 
Shell large, turbinate, solid, the surface mottled; aperture oblique, smooth within; umbilicus 
large; columella arcuate, with a callus above which extends half way around the umbilicus and is 
notched in the middle; operculum with very numerous whorls. 
Livona pica Linnaeus. 
Turbo pica Linnaeus, Syst. Nat., x, p. 763, 1758. 
Livona pica Pilsbry, Man., XI, p. 277, pi. LXI, fig. 24, 1889. 
Shell large, solid, conical, with about six rounded whorls, the surface generally slightly corru- 
gated; aperture suborbicular, oblique, umbilicus rather wide; operculum circular, multispiral, often 
