MOLLUSCA OF THE GULF OF MEXICO 1 36 



Genus FISSURIDEA vSwainson 



alternata Sa5% Jour. Acad. Nat. Sci. Phila., 2. p. 281, 1822, (as 

 Fissurclla) ; Pilsbrj^, 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, 1 901. 



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 I^amarck, Anim. s. Vert., 6, pt. 2, p. 12, 1822; Reeve, 

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

 '89; Pilsbr}^, Man., 12, p. 212, pi. 37, f. above 60, 1890. 



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

 by Pilsbry in synon5^my of alteryiata, but is more elongated 

 and with straighter sides than that species. Perhaps to be 

 classed as a variety. 



Genus PUMCTURELLA 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, 

 If" 



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. 0. 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. 



