MOLLUSCA OF PORTO RICO. 
423 
Family TRIF0R1ITE. 
Genus TRIFORIS Deshayes (em.), 1824. 
Shell small, turriculated, sharp-pointed, many-whorled, generally sinistral; aperture small, 
terminated by a short canal, and usually with a small canal at or near the posterior angle of the 
aperture; operculum paucispiral, nucleus subcentral. 
Subgenus Triforis s. s. 
Triforis turristbomae Dillwyn. 
Turbo turristhomse. Chemn., Concli. Cab., XI, p. 310, pi. CCXIII, figs. 3022 a-d, 1795; Dillwyn, Descr. Cat. Rec.Sh., p.873,1817. 
Cerithium ( Tripkora) mirabile C. B. Adams, Contr. to Conch., p. 118, 1850; Tryon, Man., ix, p. 188, pi. xxxix, fig. 53, 1887. 
Shell reversed, with about sixteen whorls which increase slowly; the suture is not impressed 
and the whorls are sculptured by two revolving rows of strong nodules, the upper row white, the 
lower chocolate-colored; the two rows of nodules cover the entire surface of the whorls and are 
separated from each other and at the suture by a groove; last whorl smaller than the penultimate 
one; aperture suborbicular, very small, with two small canals which are deflected nearly at right 
angles to the axis of the shell and are open only at the extremity. 
Length, 6; diameter, 1.5 mm. 
Mayaguez, Porto Rico, one shell with the aperture broken. 
Section MASTONIA Hinds. 
Triforis melanura C. B. Adams. Plate 58, tig. 7. 
Cerithium melanura 0. B. Adams, Contr. to Conch., p. 117, 1850. 
Shell reversed, slender, conic, the sides regularly sloping to the apex; whorls about fourteen, 
sculptured by three revolving rows of nodules, which are arranged in 'slightly oblique rows longi- 
tudinally, the sutural furrow the deepest; the middle row of nodules is a litt le smaller than the others; 
aperture small, last whorl terminating abruptly; canal short, turning slightly to the right. Color snow 
white except the apex, which is dark brown. 
Length, 5; diameter, 1.25 mm. 
Mayaguez, Porto Rico, one young shell. 
Triforis intermedia C. B. Adams. 
Cerithium ( Triphora ) intermedium C. B. Adams, Contr. Conch., p. 119, 1850. 
Cerithium htrristhomx d’Orbigny, Moll.Cubana, n, p. 155, pi. xxm, figs. 10, 12, 1845; not of Dillwyn, 1817. 
Shell with about sixteen whorls, the lower part nearly cylindrical, the upper somewhat concavely 
sloping to the sharp-pointed nucleus, with two revolving rows of nodules; on the lower whorls the 
space between the rows is widened and has an intermediate revolving thread; suture deep; tube at 
the base nearly opposite the aperture, pointing obliquely downward. The upper row of nodules 
is reddish brown, the lower is white. 
Length, 6; diameter, 2 mm. 
Mayaguez, Porto Rico, one young shell. 
Section SYCHAR Hinds. 
Triforis samanae Dali. Plate 54, fig. 18. 
Triforis ( Sychar ) samanse Dali, Blake Report, II, p. 248, 1889. 
Shell reversed, white, with twelve to fourteen whorls, cylindrical, but with the apex more rap- 
idly tapered; sculpture consisting of three coarse, close-set spiral rows of tubercles, also arranged in 
longitudinal rows, covering the whole whorl; base having three rows of tubercular cords; canal short; 
aperture short, squarish. 
Length, 10; diameter, 2.8 mm. 
Mayaguez, one badly worn shell; Samana Bay, Santo Domingo. 
Family CERITHIOPSIDtE. 
Genus SEILA A. Adams, 1861. 
Shell small, with elevated, sharp, many-whorled spire, sculptured with strong revolving ridges; 
columella twisted, with a short, truncated canal below; outer lip not thickened. 
