Page:American Seashells (1954).djvu/411

Rh Dentalium texasianum Philippi North Carolina and the Gulf States. Texas Tusk Figure 69c % to I % inches in length, thick-shelled, well-curved, hexagonal in cross- section and dull, grayish white in color. The broad spaces between the ribs are flat. Common from 3 to 10 fathoms. The subspecies cestum Henderson from Texas has numerous, cord-like riblets between the six main ribs.

Figure 69. Tusk Shells, a, Cadiihis carolmensis Bush, % inch (southeast United States), showing an enlargement of the apical end; b, apical end of Caduliis qiiadri- dentatiis Dall, % inch (southeast United States); c, Dentalium texasiamnn Philippi, I inch (southeast United States), showing cross-section at each end; d, cross-section of D. pilsbryi Rehder, i inch (west Florida); e, D. eboreum Conrad, 2 inches (southeast United States); f, D. pretiosiim Sowerby, 2 inches (Pacific Coast). Subgenus Dentale Da Costa 1778 Dentalium entale stimpsoni Henderson Stimpson's Tusk Nova Scotia to Cape Cod, Massachusetts. I to 2 inches in length, round in cross-section and dull, ivory-white in color. Region of the apex always very eroded and chalky. Surface uneven and with some longitudinal wrinkles in better preserved specimens. A poor subspecies of the north European D. entale Linne. Common from 8 to 1 200 fathoms. The subgenus Antalis H. and A. Adams is the same as Dentale. Dentalium occidentale Stimpson Western Atlantic Tusk Newfoundland to off Cape Hatteras, North Carolina.