64 MOLLUSCA OF THE GULF OF MEXICO 34 



Genus DRILL! A Gray 



ostrearum Stearns, Pr. Bost. Soc. N. H., 15, p. 22, 1872; Trj^on, 

 Man. 7, p. 197, pi. 34, f. 79, '84; Ball, Bull. 37, U. S. N. 

 M., p. 96, '89; Ball & Simpson, Bull. U. S. Fish Com., i, 

 p. 385, 1901. 



Distribution. — Hatteras to Cape Catouche, Yucatan and An- 

 tilles. 15-170 fms. West Florida: Recent, Cedar Kej^s; 

 Upper Oligocene, Tampa; Lower Miocene, Chipola beds; 

 Pliocene, Caloosahatchie beds. 



albicoma Ball, Bull. M. C. Z. 18, p. 83, pi. 10, f. 8, '89; Bull. 

 U. S. N. M., 37, p. 96, pi. 10. f. 8, 1889. 



Bistribution. — Gulf of Mexico, Lat. 23° N., Lon. 89° W., 

 84 fms. Also off Barbados, and St. Thomas. 



detecta Ball, Bull. M. C. Z., 9, p. 65, Aug., 1881: 18, p. 84, pi. 

 12, f.ii, 1889; Bull. 37, p. 96, pi. 12, f. II, '89. 



circumvoluta Watson, Jour. Linn. Soc, 15, p. 465, Nov. 1881; 

 Rept. Chall. Gastr., p, 357, pi. 21, f. i, 1885. 



Bistribution. — Gulf of Mexico, 339 fms. Also Culebra 

 Isl, W. I. 



alesidota var. macilenta Ball, Bull. M. C. Z., 18, p. 85, pi. 36, f. 

 I, 1889; Bull. 37, U. S. N. M., p. 96, pi. 36, f. I, '89. 



Bistribution. — Cape Fear, N. C. to Barbados. Gulf of 

 Mexico between Mississippi delta and Cedar Keys, iii fms. 

 Typical form of species, off Hatteras. 



eucosmia var. canna Ball, Bull, M. C. Z., 18, p, 86, 1889; Bull. 

 37, U.S. N. M., p. 96, '89. 



Distribution. — Cape Lookout, N. C, to Grenada, W. I. 

 Also Gulf of Mexico, west of Florida, 50 fms. 



leucomya Ball, Proc, U. S. N. M., 6, p. 328, pi. 10, f. 8, 1883; 

 Bull. 37, p. 96, pi. 48, f. 7, 1889; Tr. W. Inst., 3, p. 36, 

 1890. 



