EAST COAST MARINE SHELLS 



51 



PEDALION ALATA Gmelin. Winged-tree oyster. 

 Shell greatly compressed, right valve al- 

 most flat, the left slightly convex; hinge 

 line short, left valve heavier below hinge, 

 right valve with small sinus for byssal at- 

 tachment opposite the swelling outside; 

 surface smooth or scaly; interior pearly 

 layer not extending to margin; brown, pur- 

 ple or blackish in color; young examples 

 often rayed. Length 3 inches. 



The "tree oyster" attaches itself 

 to mangroves or any solid object in shallow 

 water. It is gregarious, many shells often 

 being fastened together. The writer ob- 

 served it living in Angel Fish Creek on the 

 Florida Keys. 



PI. 5, Fig. 4 



Florida; Bermuda; West Indies 



PEDALION LISTERI Hanley. Usually a high 

 elongated shell; well developed at base; 

 three to seven pits in each tongue-like 

 process of porcellaneous material in base; 

 Rolor variable, often rayed with a lighter 

 shade. Height 35 mm. 



PI. 5, Fig. 8 



Florida Keys and West Indies 



PEDALION SEMIAURITA Linne. Shell small, 

 solid, very irregular, large pits in hinge 

 line of each valve; byssal notch obscure. 

 Height 16 mm. 



It lives in the crevices of rocks 

 and corals. As variable as the oyster It 

 largely conforms to the surface and other 

 local conditions. At the Blowing Rocks, 

 near Jupiter, Florida, it is plentiful not 

 far from the high-tide mark. 



PI. 5, Fig. 5 



Southern Florida and West Indies 



Family Ostreidae 



Shell irregular, Inequlvalve, the 

 larger valve adhering to som'e solid object, 

 the outer moving forward as the shell ma- 

 tures; excessively variable according to 

 the position during life and for this rea- 

 son difficult to differentiate the species. 



GENUS OSTREA Linne 1758 (OYSTERS) 



OSTREA CRISTATA Born. Crested Oyster. 

 Shell solid, very irregular, upper valve 

 concave or convex; valves with long tubu- 

 lar clasping processes for attachment to 



mangroves or other solid objects; edge of 

 valves sharply plicate-serrate, forming 

 interlocking teeth; interior border with 

 wart-like ridge; umbones irregular, one in 

 lower valve the longer, its hinge area 

 grooved in middle; color brown, reddish or 

 purple. Largest examples about 3.5 inch- 

 es. 



A more variable shell than 0. 

 virginica. 



PI. 14, Fig. 9 



Tampa, Florida to the West Indies 



OSTREA EQUESTRIS Say. Horse Oyster. Shell 

 small, six to twelve teeth of larger valve 



received into corre- 

 sponding cavities of 

 the smaller valve; 

 large valve depressed 

 but a little folded; 

 other valve convex 

 and attached to some 

 foreign object; hinge 

 narrow and curved. 

 Fig. 32 

 Cape Hatteras, 

 North Caro- 

 lina to Flor- 

 ida 



Fig. 32 

 Ostrea equestris 



OSTREA FRONS Linne. Leafy Oyster. Shell 

 thin, broad, adhering to roots by shelly 

 lobes, purple-brown; hinge of left valve 

 small; generally attached crosswise to 

 some external object. 



Johnson reported this species from 

 St. Augustine attached to a sea-fan (Gor- 

 gonia) . Length 45 mm. 



PI. 6, Fig. 5 



Jupiter Inlet, East Florida to 



Barbados 



OSTREA PERMOLLIS Sowerby. Shell more or 

 less four sided, the two edges next to um- 

 bones comparatively straight; compressed, 

 subequivalve, somewhat golden colored and 

 bluish-white inside, with tendency toward 

 greenish at edges; hinge narrow; upper 

 valve slightly convex and with a soft 

 brownish epidermis; concentric sculpture 

 wavy and irregular. Height 1.5 inches. 



It has been taken in the bread 

 sponge at Sanibel, Florida. 



PI. 6, Fig. g 



Florida 



