EAST COAST MARINE SHELLS 



45 



on the white ground; ligament short, not 

 straight; teeth blunt and rounded; left 

 valve with tooth forward and pit behind; 

 right valve with pit in front and tooth be- 

 hind; border indistinctly crenulated. 

 Length 27 mm,, height 30 mm. 



A much smaller species than C. 

 macerophylla, also separated by the ornate 

 color patterns and red stains of the free 

 valve. 



PI. 14, Fig. 3 



Florida Keys and West Indies 



GENUS ECHINOCHAMA Fischer 1887 

 (SPINY CHAMA) 



ECHINOCHAMA ARCINELLA Linne. Shell in- 

 flated, solid; umbones curved forward over 

 a large wide lunule; ligament partly in- 

 side, surface covered with coarse granula- 

 tions or small pustules, arranged in series 

 and with eight to twenty curved ribs; large 

 cardinal tooth in right valve which fits 

 into pit in left valve, left valve with 

 one curved cardinal tooth; color white out^ 

 side, white or purplish within. Height 

 55 mm. including spines. 



The young shell is attached by the 

 right valve in front of the umbone but lat- 

 er in life becomes free although always 

 carrying the attachment scar. Sometimes 

 they are found in clusters. When first 

 freed from the egg the animal is unattached, 

 the shell being crimson or brovm. 



Single valves are often common up- 

 on the west Florida beaches including Marco. 

 Living examples are obtainable by dredging 

 in a few feet of water off Sanibel. 



Fine fossil specimens have been 

 taken in the Pliocene beds near Clewlston, 

 Florida. 



PI. 14, Fig. 1 



Cape Hatteras, North Carolina to 



West Indies 



Family Thyasiridae 



Lunule minute, usually deeply im- 

 pressed; mostly minute shells. 



THYASIRA GOULDII Philippi. Shell minute, 

 almost equilateral; interior with minute 

 radiating lines; very small cardinal tooth 

 and no lateral ones; ligament rather large, 

 partly concealed. Length 6 mm. Depth 

 range 5-400 fathoms. 



Go\ild reports it as taken from cod- 

 fish stomachs and its preference for sandy 

 bottoms. 



PI. 73, Fig. 2 



Greenland to Connecticut; Pacific 



THYASIRA OBESDS Verrill. 

 PI. 73, Fig. 12 



Family Ongiilinidae (Diplodontldae) 



Animal like Lucinidae except in 

 development of the gills; shell hinge with 

 lateral teeth obscure or absent, margin of 

 valve plain, subcircular in shape. 



GENUS TARAS Risso 1826 

 (Diplodonta Bronn 1831) 



TARAS VENEZUELENSIS Dunker (T. punctata 

 Say) . Shell squarish, orbicular, valve 

 slightly longer than high; exterior and in- 

 terior somewhat dull; short radiating 

 striae not always visible; cardinal teeth 

 minute, one in each valve bifid. Length 

 11.5 mm., height 10.5 mm., thickness of 

 both valves 7 mm. Depth range 0-180 fath- 

 oms. 



PI. 22, Fig. 12 



Gulf of Mexico and Florida Strait 



Family Cyrenellidae 



GENUS CYRENOIDA Joannis 1835; 

 Cyrenella Deshayes 1835 



CYRENOIDA FLORIDANA Ball. Shell rounded, 

 small, thin; epidermis pale yellow, silky; 

 siirface almost smooth; interior margin pol- 

 ished, smooth; pallial line indistinct, of- 

 ten broken; ligament short, external. 

 Length 10-13.5 mm., alt. 12.5 mm., diam. 

 8 mm. 



The shell resembles Diplodonta; the 

 animal is much like Lucina, the foot being 

 long and slender. 



It has been taken abundantly in the 

 outer edge of mangrove swamps, skirting the 

 bay, in the vicinity of Miami, Florida. 



PI. 16, Fig. 11 



Brunswick, Georgia south to the 



Everglades, north to Charlotte 



Harbor, west Florida 



