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270 1 5 short axial ribs per whorl. Spiral threads numerous and fine. Sinus small, its posterior end round, its opening narrow. Not uncommon below low water under rocks. C. sanibelensis Bartsch and Rehder is similar, but i inch in length, with 9 longer and wider axial ribs, with a large slit, and colored orange-chestnut with white between the ribs. Uncommon around Sanibel Island. Subgenus Crassispirella Bartsch and Rehder 1939 Crassispira ostrearum Stearns Oyster Turret Plate 26n North Carolina to south half of Florida. Cuba. % to % inch in length; light yellow-brown to chestnut. Sinus U-shaped. About 20 weakly beaded axial ribs per whorl. Just below the suture there is a single, smooth, strong spiral cord. Spiral threads moderately strong to weak (16 to 20 on the last whorl, 4 between sutures). Lower part of outer lip thin and strongly crenulate or wavy. Common from low water to 90 fathoms. C. tampaensis Bartsch and Rehder is very similar, and may be this species. Genus Cerodrillia Bartsch and Rehder 1939 Cerodrillia perry ae Bartsch and Rehder Perry's Drillia West coast of Florida. /4 inch in length, flesh-colored, with a broad, golden-brown band around the periphery. 8 to 9 axial ribs per whorl. Faint spiral lines present. Not uncommon. C. tbea has shorter axial ribs and is uniform chocolate- brown. Cerodrillia thea Dall Thea DriUia Figure 57f West coast of Florida. !4 inch in length, thick-shelled, with a glossy-brown finish, and with the short, slanting ribs cream in color. Outer lip prominent. Sinus deep and U-shaped. Uncommon in shallow water. Genus Monilispira Bartsch and Rehder 1939 Momlispira albinodata Reeve White-banded Drillia Southeast Florida and the West Indies. V2 inch in length, resembling a Cerithimn in shape; color dark blackish