68 Marine Shells of the Western Coast of Florida 



stout external ligament; one cardinal tooth in each valve, with two 

 anterior lateral and one posterior lateral in right valve and a con- 

 trary arrangement in left valve; interior reddish hrown; margins 

 serrate. 



Genus PAPYRIDEA Swainson, 1840 

 I'apyridea solenifomiis'''' (Bruguiere)(P. spinosum Meuschen) PI. 13, fig. 74 



Alt., 28; length, 35 mm. Shell thin, transversely elongate, gap- 

 ing at posterior end; ground color light mottled with rosy brown; 

 brownish periostracum; pure yellow specimens occur; numerous 

 low, flat ribs, smooth over central area, slightly spinose over anterior 

 portion, sharply spinose posteriorly and prolonged beyond the gaping 

 margin; cardinal and lateral teeth; interior pinkish, sometimes rayed 

 with darker shade. 



Genus TRIGONIOCARDIA Dall, 1900 

 Trigoiilocardia"^ media (Linne) PI. 41, fig. 293 



Alt., 32; length, 28 mm. Shell inequilateral, semirounded, 

 creamy white, splotched with brown; darkest on posterior side which 

 is flat heart-shaped; anterior side, round heart-shaped; umbos high 

 and semirounded; 22 serrated ribs on rounded anterior slope, 12 

 smoother ribs on posterior, flat heart-shaped slope; margin mod- 

 erately serrated, closely interlocking; interior white. 



Genus LAEVICAKDIUM Swainson, 1840 

 Laevicardium laevig'atum^" (Linne) [L. serratum (Linne)] PI. 13, fig. 75 



Alt., 65; length, 54 mm. Shell oblique posteriorly downward, of 

 alabasterlike quality, ivory color, brown or ashen epidermis; umbos 

 round; traces of narrow ribs; cardinal and lateral teeth; interior 

 cream color, often pinkish; internal margins finely serrate. 



Laevioardhini niortoni (Conrad) PI. 13, figs. 76a, b 



Alt., 16; length, 15 mm. Shell small, thin, smooth, inflated, 

 nearly round; cream color irregularly patterned with brown; umbos 

 round, flat; faint concentric striations, minutely papillose; interior 



"^ Lat., papyrus, paper; soleniforma, like a solen; spina, thorn. 

 "** Gr., trigonos, three-cornered, triangular; Kardia, heart. 

 ^" Lat., larvis, smooth ; Lat., sena, a saw. 



