212 GLYPHIS. 



margin finely crenulated ; pit back of the hole-callus deeply exca- 

 vated. 



Length 36, breadth 22, alt. 16 mill. (Largest specimen seen.) 

 Length 28, breadth 18, alt. 12 mill. (Average West Indian spec- 

 imen). 



Chesapeake Bay to Trinidad, including the entire West Indies; 

 Bermuda (Heilprin) ; Vera Cruz and Progreso (Baker) ; Nicaragua. 



Fissurella alternata SAY, Journ. Acad. Nat. Sci. Phila. ii, p, 281 r 

 June, 1822. BINNEY'S edition of Say's Complete Writings, p. 73. 

 DALL, Blake Gastrop. p. 407, with var. Sayi ; and Catal. Mar. 

 Moll. S-E. U. S., in Bull. 37, U. S. Nat. Mus., p. 170. Glyphis al- 

 ternata Say, BAKER, Proc. Acad. Nat. Sci. Phil. 1891, p. do. Fis- 

 surella fumata RVE., Conch Icon. f. 63. F. Dysoni RVE., I. c. f. 

 86. F. larva RVE, /. c.. f. 98. F. metcalfii RVE., 1. c. f. 75. Sow- 

 ERBY, Thes. iii, p. 192, f. 140-142. F. viminea RVE., /. c, f. 105. 

 F. cayenensis LAM., An. s. Vert, vi, pt. 2, p. 12. DELESSERT, Rec. 

 de Coq. t. 24, f. 5. REEVE, Conch. Icon. f. 82. SOWB., Thes., p. 

 197, f. 101. 



This is a very finely, sharply sculptured form, much more finely 

 clathrate than G. listeri, and having the concentric threads raised 

 into minute scales on the ribs. I have seen no living specimens 

 from north of Chesapeake Bay, but dead shells are occasionally 

 washed up on the beach at Cape May, N. J. Dr. Sharp collected 

 the species at Trinidad. The more prominent riblets number from 

 18-24. 



F. larva Rve. (pi. 37, fig. 57) is a dark form ; F. dysoni Rve- 

 (pi. 37, fig. 54) is the common black-banded variety ; F. metcalfii 

 Rve. (pi. 39, f. 91), and F. viminea Rve. (pi. 39, f. 80) do not seem 

 to be distinct. The figures of F. cayenensis Lam. given by Deles- 

 x sert, Reeve and Sowerby, as well as Lamarck's description, indicate 

 that that supposed species also belongs here. Cayenensis is rather 

 an elongated shell, more straight-sided than the usual alternata. 

 Specimens before me, from St. Thomas and other places, agree with 

 the Lamarckiau type. Reeve's figure of cayenensis is given on pi. 

 37, fig. above 60. 



Var. fumata Reeve (pi. 39, fig. 1). Whitish, rayed with olive- 

 ash ; bluish around the orifice. This form is before me from Trini- 

 dad. It is less sharply sculptured than the type. 



Var. Sayi Dall. Smaller, olivaceous, color-rays faint or absent. 

 This is the deep water form. 



