426 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Cerithium variabile C. B. Adams. 
Cerithium variabile C. B. Adams, Proc. Bost. Soc. Nat. Hist., II, p. 5, 1848. 
Cerithium, variabile Sowerby, Conch. Icon.,xv, pi. xm, tig. 91,1865. 
Shell small, solid, with scarcely rounded whorls, which are sculptured by three revolving rows 
of tubercles, with about seven or eight rows on the last whorl; opposite the outer lip there is a varix, 
and there are varices scattered over the whorls; outer lip thick, varicose; aperture small. Color 
brownish or blackish, often variegated with white. 
Length, 12; diameter, 5 mm. 
Mayaguez; Boqueron Bay; Puerto Real; San Juan; Ponce; Arroyo, Porto Rico; Ensenada Honda, 
Culebra; Florida; West Indies. 
Cerithium minimum Gmelin. 
Murex minimus Gmelin, Syst. Nat., p. 3564, 1792. 
Potamides minimus Tryon, Man., IX, p. 167, pi. xxxiv, figs. 9-11, 1887. 
Shell only moderately solid, with low, longitudinal ribs and faint revolving ridges, which cut 
the longitudinal ribs more or less into nodules. In addition to the revolving ridges there are fine 
revolving threads in their interstices. The aperture is rather large; the basal canal is turned sharply 
to the left. Color varying from jet black to ashy, variously banded. 
Length, 15; diameter, 6 mm. 
Puerto Real; Ponce; San Juan; Mayaguez, Porto Rico; Ensenada Honda, Culebra; West Indian 
region generally; Florida. 
This species is quite close in appearance to C. variabile. It is generally less solid and more 
glossy than that species and has more distinct longitudinal ribs. Its aperture is generally larger and the 
basal canal more distinctly turned to the left. Still, there are specimens that are difficult to name. 
Genus PYRAZUS Montfort, 1810. 
Shell elongated; whorls angular; aperture subquadrangular, prolonged below; canal almost 
straight; lip dilated. 
Pyrazus degeneratus Dali. 
Cerithium (Pyrazus) septemstrialum var. degeneratum Dali, Bull. Mus. Comp. Zool.,ix, p. 115, fig. 11,1894. 
Shell thin, brightly colored, finely spirally striate, scarcely sculptured longitudinally, with about 
six or seven whorls, which are slightly shouldered above; aperture subrhombic; outer lip thin, 
dilated; canal open. 
Length, 12; diameter, 4 mm. 
San Juan Harbor, Porto Rico, one shell. 
Genus BITTIUM (Leach) Gray, 1847. 
Shell small, elongated, with many granulous whorls, which have irregular varices; basal canal 
short, not curved; outer lip with a varix behind; columella simple; operculum subcircular, pauci- 
spiral; nucleus central. 
Subgenus Diastoma Deshayes. 
Bittium varium Pfeiffer. 
Cerithium varium Pfeiffer, Arch.ftir Naturg., 1840, p. 256. 
Bittium, varium Tryon, Man., IX, p. 152, pi. XXIX, fig. 86, 1887. 
Shell with seven or eight more or less rounded whorls, with a distinctly marked suture; 
sculpture consisting of delicate, longitudinal, slightly curved ribs, which are cut into nodules by 
revolving grooves; there are about three of these grooves on each whorl; on the body whorl there 
are additional grooves extending over the base, which is scarcely nodulous; outer lip somewhat 
patulous; aperture oval; canal not produced, feeble; at some distance back of the lip there is a 
nearly smooth varix. Color varying from purplish white to purple brown, variously clouded. 
Length, 5; diameter, 1.8 mm. 
Mayaguez, Porto Rico, one broken shell. 
