Shell with eight whorls, the first one and a half smooth, the others with delicate growth lines, and having about seven or eight strong, slightly curved rilxs; these ribs are nearly continuous from the apical whorls to the base of the shell, being only slightly cut by the narrow suture, and becoming a little fainter at the faintly impressed fasciole; varix distinct, canal somewhat drawn out.. Color generally that of wet tea leaves.
Length, 15 mm.; diameter, 4.5 mm.

Shell small (to 16.9 mm), narrowly to stoutly fusiform; truncate anteriorly, body whorl about 60% of length, and surface glossy; sculpture of axial ribs; whorls convex, suture impressed. Protoconch of approximately 1,5-1,75 smooth, semi-translucent whorls, the first partially immersed in the second at its tip. Axial sculpture of well-spaced ribs, 7-9 on penultimate, 4-8 on last to varix, interspaces about twice their width, ribs run from suture-to-suture on spire whorls, evanesce early on shell base, straight to oblique, broadest and highest, sometimes knob-like, at shell periphery, lower, narrower, sometime obsolete on last whorl, and hooked to the left in sulcal area; rib profile convex, periphery below mid whorl on spire whorls; rib crests round at periphery and ridged on shoulder. Spiral sculpture limited to faint spiral ridges on shell base, below periphery, and distinct ridges on anterior fasciole. Sulcus obscure in some, marked by the presence of curved growth striae, to well-marked by reduced ribs, narrowed and curved, or obsolete ribs as in the later whorls of larger specimens. Varix cup handlelike, Vi-turn from edge of outer lip. Outer lip thin, with a strengthening rib very close to lip edge in mature specimens; edge forming an arc from and congruent with anal sulcus to the stromboid notch; stromboid notch shallow. Anal sulcus deep, U-shaped, located on shoulder slightly set off from suture; sides of sinus divergent. Inner lip margined, thick along anterior canal, wider but thinner on parietal wall, and forming a lobe at junction with outer lip. Anterior canal very short, bent slightly to the right viewed ventrally, open and unnotched. Color light to dark caramel; usually rib crests just white, but sometimes a continuous mid-whorl white band present, and rarely a second, thin white band on shell base.

The average length of 68 specimens is 11.28 mm (5.3-16.9 mm), and their average W/L is 0.390. C thea is narrow for Cerodrillia, most members of the genus have a W/L > 0.40. Individual specimens are uniformly colored, ranging from very dark brown to fairly light. Geographic variation is exhibited by this species and may be due to population isolation and habitat influences. Specimens from the Bahama Is. have more angular varices; those from the Florida Keys are smaller and darker, and from the central western coast of Florida are largest and generally colored like the types. Identification. Cerodrillia thea has a shell that is high-spired and uniformly light to dark caramel in color with lighter ribs that are noticeably oblique, traits that distinguish it from species with which it is often confused. C. thea is most similar to C harryleei, new species and C. sanibelensis, new species, both from W Florida. From C harryleei it differs in possessing slightly more ribs that are more oblique and less nodulose (7-9 versus 5-6 on the penultimate whorl). Also, C harryleei has a faint brown spiral stripe in specimens examined so far, which is absent in C thea. From C sanibelensis it differs in possessing a narrower shell (average W/L ratio - 0.390 versus 0.405), slightly more ribs that are more oblique (7-9 versus 6-7 on the penultimate whorl of individuals with varices), and darker color (light to dark caramel versus white to light orange brown).

W Florida (Okaloosa Co. and southward); Florida Keys; E Florida (Palm Beach Co. and southward); Bahama Is. (Grand Bahama I., Bimini Is., Abaco I.; Eleuthera I.); Cuba (north coast of Matanzas Prov.). Localities appearing in the published literature that are just outside this range and have yet to be confirmed are: North Carolina; E Florida (north of Palm Beach Co.); Alabama (Gulf coast); Louisiana; and Cuba (west and south of its NW coast). Reports of specimens from further afield are unlikely to be C thea. Habitat reports are from the littoral zone to 27 m depths, from locations around sand bars of inside waters (Perry, 1940b: 165), in tide pools at low tide, bays, and from shallower waters offshore. Substrates range widely from mud flats, to sand and rubble bottoms in grass.