Shell small (to 10.2 mm), fusiform, glossy, up to 8,75convex whorls, periphery slightly below spire whorl's midpoint; suture appressed, scalloped by ribs on preceding whorls; last whorl about 58% of total shell length. Shell sculpted with axial ribs. Protoconch of 1,75 smooth round whorls, the first not immersed; protoconch lip discernable. Axial sculpture of low, broad ribs that stretch from suture-to-suture on the spire whorls, but evanesce on shell base, just below whorl periphery. Ribs broadest and most prominent just below midpoint of whorl, appearing almost knob-like, lowest to almost obsolete on shoulder of later whorls. Fine growth striae present on shell surface. Spiral sculpture a few faint ridges on shell base, and about 6 stronger ridges on anterior fasciole. Sulcus concave, with low, almost obsolete (on later whorls), narrow axial ribs that extend to the suture. Varix is cup handle-like, angled at its periphery, not evenly rounded. Outer lip juts out from the base of the varix, is thin; lip edge forms a low arc, beginning at the anal sinus and ending at the stromboid notch, edge bent inward approaching the anal sinus, and ruffled over the stromboid notch anteriorly. A strengthening rib may be present near the lip's edge. Anal sinus deeply notched, U-shaped, and positioned midway along the shoulder, slightly constricted at its opening by a parietal lobe. Inner lip moderately wide, widest in parietal area, margined, ends in a lobe posteriorly, at its junction with the outer lip. Anterior canal short, broad, open, and unnotched; anterior fasciole not swollen. Color base light olive brown or brown, and patterned with a faint peripheral brown line, rib crests and varix lighter, almost white.

Cerodrillia harryleei has all the shell characters diagnostic of Cerodrillia: ribs from suture-to-suture, although quite reduced in the sulcus of later whorls, a cup-handle-like varix just behind the anal sinus, and spiral sculpture limited to the shell base and anterior fasciole. Its ribs are reduced in the sulcus and fade quickly below the whorl periphery on the shell base. Ribs are not as oblique as in most Cerodrillia. Variability. The average total length of three specimens is 8.83 mm (6.8-10.2 mm), and their average W/L is 0.438. Identification. Cerodrillia harryleei is most similar to C thea (Dall, 1884) and C clappi Bartsch & Rehder, 1939. It differs from the former in possessing straighter ribs (the ribs of C thea are noticeably oblique) that are knoblike at the whorl periphery, and with slightly fewer ribs (6-7 versus 7-9 on the penultimate whorls of mature specimens). Cerodrillia harryleei is olive brown, not the brown of C thea. Also, C. harryleei has a faint peripheral spiral brown line absent in C. thea. Cerodrillia clappi is of similar size but narrower (W/L = 0.392 versus 0.438) may also have a narrow peripheral brown spiral line but its ribs are more numerous (9 versus 5-9 on the penultimate whorl of mature specimens) and are more slender than the ribs of C. harryleei, not produced into knobs at the whorl periphery. It is also a different color—white not olive brown.

E side of Seahorse Key, Cedar Keys, Levi Co., W Florida, in 5-6 m. Range and habitat. W Florida (Jefferson Co.; Levy Co.) in 5-6 m.