54 Marine Shells of the Western Coast of Florida 



umbos, anterior, not terminal; hinge margin straight; valves round- 

 ed; interior nacreous, margins smooth. 



Found in mud between tide marks, usually in inside waters. 



Subgenus GKEGARIELLA^o Monterosata, 1883 

 Modiolus opifex-^i (Say PI. 7. fig. 40 



Alt., 7; length, 17 mm. Shell smooth save for growth hues, oval, 

 attenuated to a rounded point posteriorly; shell light colored 

 covered with brown epidermis; valves carmated to form a flat hmge 

 area; epidermis fringed and ragged along the keel; mterior pearly. 



Dredged, taken from cavities in fragments of rock and coral. 



Genus BOTULAs^ Morcli, 1853 

 Botulii oastaneass (gay) Pl. 7, fig. 41 



Alt., 6; length, 15 mm. Shell oblong, smooth, inflated, purplish 

 beneath shining brown epidermis, purplish within; anterior mar- 

 gm rounded; posterior margin rounded; umbos high, subterminal; 

 depressed byssal notch anterior to center. 



Shallow and moderate depths. 



Botula fnsca5-i (Gmelin) PI. 7, fig. 42 



Alt., 4; length, 12 mm. Shell oblong, smooth, inflated, dark- 

 brown shining epidermis. Anterior extremity rounded; posterior ex- 

 tremity with high, rounded umbos, subterminal and almost in con- 

 tact. Juvenile shells have a more or less rhomboidal outline. 



Shallow to moderate depths. 



Genus LITHOPHAGA Roding, 1798 

 Lithopha^'''5 antillarum (d'Orbigny) PL 40, figs. 289a, b 



Alt., 12 or more; length up to 50 mm. Shell white with thick, 

 dark-brown epidermis; much elongated oval, date-shaped; dorsal 

 and ventral margins nearly parallel, anterior and posterior margins 

 rounded; umbos suppressed; fine basal ribbing, growth lines most 



50 Lat., grcgarius, belonging to the herd, common. 



^^ Lat., opifex, an artificer. 



5- Lat., botula, a sausage. 



^^ Lat., castanea, chestnut. 



5"* Lat., fuscus, tawny. 



*"* Gr., lithos, stone; phagein, to eat. 



