MOLLUSCA OF PORTO RIOO. 
363 
Tornatina candei d’Orbigny. Plate 57, fig. 7. 
Bulla candei d’Orbigny, Moll. Cubana, I, p. 128, pi. iv Ms, figs. 1-4, 1842. 
Shell small, subcylindrical, widest at the shoulder; spire low conical; surface smooth except for 
faint growth lines, shining, milky white. Outer lip advanced in the middle; columellar fold moderate. 
Length, 2.5; diameter, 1.5 mm. 
Mayaguez, Porto Rico, five worn specimens. 
Genus VOLVULA A. Adams, 1850. 
Shell subcylindrical or long oval, tapering at both ends, body whorl produced into a beak or spine 
above. Spire concealed; aperture as long as shell, narrow, produced above, columella with a slight fold. 
Type, V. acuminata Bruguiere. 
Volvula oxytata Bush. Platfe 57, fig. 8. 
Volvula oxytata Bush, Trans. Conn. Acad. Sci., vi, p.468, pi. lv, fig. 12, 1885. 
Shell thin, cylindrical, with a sharp, spike-like apex and a tapering, rounded anterior end, 
shining, with four or five very fine, revolving, punctured lines at each, end, and exceedingly faint 
microscopic stria- on intervening surface. Inner lip slightly reflected anteriorly over an umbilical chink. 
Length, 2.5; diameter, 1 mm. 
Mayaguez, Porto Rico, three shells. 
Volvula acuta d’Orbigny. 
Bulla acuta d’Orbigny, Moll. Cubana, I, p. 126, pi. iv, figs. 17-20, 1842. 
Shell obovate, being widest near the spire, attenuated above and below, thin, white, with revolving 
stride at the base, not perforated; columella scarcely flexuous. 
Length, 2.5; diameter, 1 mm. 
Mayaguez, Porto Rico, three worn shells. 
Genus RETUSA Brown, 1827. 
Shell small subcylindrical, with raised flat or sunken spire; aperture as long or nearly as long as 
the shell, narrow above, dilated below. Columella with or without a small fold. 
Retusa ceelata Bush. 
Cylichna cselata Bush, Trans. Conn. Acad. Sci., vi, p. 468, pi. xlv, fig. 15, 1885. 
Shell small, somewhat conical, truncated above; spire concealed in a deep pervious pit, within 
which one or two whorls are seen; the upper end of the shell is sculptured with beautiful, flexuous 
ribs which fade out a short distance down the body whorl; the basal part of the shell is rounded and 
sculptured with a few revolving, punctate lines; aperture narrow, suddenly becoming wider below, 
slightly drawn out at the base; columella faintly truncate below, with a minute chink behind it. 
Length, 3; diameter, 1.5 mm. 
Mayaguez, Porto Rico, two slightly worn specimens. 
Family BULLIDtE. 
Genus BULLA Linnseus, 1758. 
Shell elliptical or ovate, compactly involute, generally solid and with a mottled color pattern; 
spire sunken, umbilicated. Aperture as long as shell, rising above vertex, narrow above, expanded 
below; lip simple, columella short and concave. Type, B. ampulla Linnseus. 
Bulla amygdala Dillwyn. 
Bulla amygclalus Dillwyn, Descr. Cat. Rec. Sh., I, p. 480, 1817. 
Bulla amygdala Pilsbry, Man. xv, p. 329, pi. xxxvm, fig9. 49, 50, 62-65, 1893. 
Shell oblong, narrower toward the vertex, solid, rather dull, clouded and mottled with purplish 
on a pale ground. Surface generally without microscopic revolving stria-, but having a few spaced 
lines at the base, and rarely a few at the vertex; umbilicus deep, striated within. Outer lip thick, 
callous where it rises from the vertex, its outer part straight. Columella arcuate, with a very heavy 
reflected callus, which has a chink behind it. 
