l66 MOLLUSCA OF THE GULF OF MEXICO 1 36 



Genus FISSURSDEA Swainson 



aliernata Sa}^, Jour. Acad. Nat. Sci. Phila., 2. p. 281, 1822, (as 

 Fissurdla); Pilsbry, Man., 12, p. 211; pi. 37, f. 50-53, pi. 61, 

 f. 24, 25, '90; Dall and Simpson, Bull. U. S. Fish Com., i, 

 p. 450, lOOI. 



Distribution. — Chesapeake Bay through the Antilles to 

 Trinidad Isl. and Fernando Noronha, Brazil. Gulf coast: 

 Cedar Keys, Fla. ; Galveston, Corpus Christi, Texas; Vera 

 Cruz and Progreso, Mexico. Also south of Nicaragua. 1-50 

 fms. Pliocene of South Carolina. 



cayenensis Lamarck, Anim. s. Vert., 6, pt. 2, p. 12, 1S22; Reeve, 

 Conch. Icon., f. '82; Dall, Bull, 37, U. S. N. M., p. 170, 

 '89; Pilsbry, Man., 12, p. 212, pi. 37, f. above 60, 1890. 



Distribution. — Cedar Keys, Fla. to St. Ducia, W. I. Placed 

 by Pilsbry in synon3miy of alternata, but is more elongated 

 and with straighter sides than that species. Perhaps to be 

 classed as a variety. 



Genus PUi^CTURELLA Lowe 



trifolium Dall, Bull. M. C. Z., 9, p. 76, '8i; 18, p. 403, pi. 26, f. 

 8, 8b, '89; Bull. 37, U. S. M. N., p. 168, pi. 26, f. 8, 8b, 

 1889. 



Distribution. — Yucatan Strait, 640 fms. 



watsoni Dall, Bull. M. C. Z., 18, p. 403, '89; Bull. 37, U. S. 

 N. M., p. 168, '89. 



Distribution. — Off Yucatan, at 200 fms. Also off Cuba and 

 Barbados. 



circularis Dall, Bull, M. C. Z., 9, p. 75, '81; 18, p. 403, pi. 26, 

 f. 7, 7b, '89; Bull. 37, M. S. N. M., p. 168, pi. 26, f. 7, 

 7b, '89. 



Distribution. — Florida Strait and the West Indies. 



