56 Marine Shells of the Western Coast of Florida 



shells are all white and fragile. The most interesting character of 

 the Periplomas is the existence of a small triangular-shaped litho- 

 desma which is within the shell and lies between the spoon-shaped 

 tooth and the anterior cardinal margin. The mollusks are herma- 

 phroditic. 



Genus PERIPLOMA Schumacher, 1817 

 Periploina''" iiiaequivalve Schumacher PI. 8, fig. 46 



Alt., 8.5; length, 14 mm. Shell light and fragile, white; inequi- 

 valve, left valve smaller; inequilateral, posterior extremity truncated 

 and a little gaping; umbos small, near posterior extremity and 

 directed posteriorly; an oblique ridge or keel from umbo to posterior 

 end of ventral margin; concentric growth hnes; interior pearly; one 

 spoon-shaped tooth in each valve for the reception of hinge cartilage. 



Found in sand bottoms near low tide mark. Preyed upon by 

 Marginella apicina. 



Family PAXDORIDAE 



Distribution of the Pandoridae is quite general in all seas. On 

 the East American coast they are found from the Arctic Ocean to 

 the Gulf of Mexico. 



The shells are small and usually free; inequivalve; roughly semi- 

 lunar; white or brownish with a thin periostracum. The umbos are 

 inconspicuous and the hinge consists of lamelliform plates which 

 take the place of teeth, and an internal ligament lodged in an oblique 

 sulcus. There is a lithodesma. Non-byssiferous. 



Genus PANDORA Chemnitz, 179.5 

 I'andora'i triliiicahi Say PI. 8, figs. 47a, b 



Alt., 15; length, 29; diam., 3.5 mm. Shell white, smooth, growth 

 lines parallel with ventral margin; thin, light-colored, polished 

 epidermis; slightly inequivalve; inequilateral; umbos at extreme 

 anterior end, not projecting; hinge internal, below umbos, lamellar 

 plates replace teeth; a ligamentary fossa is present. Posterior part 

 of shell much prolonged, with a scimitar curve upward; posterior 



'•^ Gr., peri, around, about; ploimos, fit for sailing; periplomenos, moving. 

 "1 Gr., pan, all, doron, gift — Pandora, all-gifted, a mythological person. 



