36 Marine Shells of the Western Coast of Florida 



Aiiadara transversa (Say) PI. 1, figs. 7a, b; 



PI. 2. fig. 7c 

 Transversely oblong, rhomboidal, thirty-two to thirty-five ribs placed at 

 nearly the length of their own diameter distant from each other. Apices sep- 

 arated by a long, narrow space, and situated at the termination of the posterior 

 third of the length of the hinge margin; extremities of hinge margin angulated; 

 anterior edge, superior moiety rectilinear; posterior edge rounded; inferior 

 edge nearly rectilinear, or very obtusely rounded; on the hinge space one or two 

 angulated lines are drawn from the apex, diverging to the hinge edge. Length 

 less than seven-twentieths of an inch, breadth one and one-fifth inches . . . 

 Known by apex being situated opposite one-third distance from posterior ter- 

 mination of hinge margin.^" 



A small Anadara (PI. 2, fig. 7c), differing in certain definite 

 characters from the established form Anadara transversa (Say), is 

 found on both the Atlantic and Gulf Coasts of Florida. Shells of the 

 two types are commonly associated without differentiation; com- 

 parison in regard to shape, relative proportions, sculpture, and 

 dentition reveals differences which seem to be sufficiently well marked 

 and constant to warrant distinction. 



Both types are found on sandy bottoms. The depth range of 

 A. tra?isversa appears to be less than that of the aberrant form. 

 From the littoral zone to six fathoms. 



.Vnadara''^ lienosa floridaiia (Conrad) (A. sccticosta Reeve) PI. 2, fig. 8 



Alt., 50; length, 90; diam., 45 mm. Heavy, white, thick brown 

 epidermis; equivalve; inequilateral; umbos somewhat incurved and 

 flattened; hinge margin straight, anterior and ventral margins 

 rounded, posterior margins straight and obliquely angled with hinge 

 margin. Thirty-five ribs which markedly widen as they diverge, a 

 deep central groove in each rib which does not extend over um- 

 bos and is absent from the rounded posterior ribs; fine ribbing crosses 

 both ribs and the concave intercostal spaces. This fine, tranverse rib- 

 bing serves — as in other Anadaras — for attachment of the scales of 

 the epidermis. Hinge typical. Interior of valves show delicate hnear 

 markings; margins dentate; well-impressed muscle scars and pallia! 

 line; byssus long, thin, flat, and broken up into many narrow 

 strands. 



^^ Say's description, read July 24, 1821. Journal Academy of Natural Sci- 

 ences, vol. 2, pt. 2. 

 ^* Lat., lien, lienosa, spleen, splenetic. 



