28 



EAST COAST MARINE SHELLS 



lozenge-shaped zone between umbones; color 

 purplish brown Inside and out; epidermis 

 shaggy, extending outward on posterior 

 ridge. Length 1-2 inches. 



Pi. 3, Fig. 1 



North Carolina to Gulf of Mexico; 



West Indies 



SUBGENUS BARBATIA Gray 1847 



ARCA BARBATA Llnne. Bearded Ark. Shell 

 oblong, usually with rounded ends, slight- 

 ly gaping below; umbones one foirrth dis- 

 tance back from anterior end; surface 

 closely sciilptured by different sized radi- 

 ating ribs which are crossed by ridges as 

 in A. Candida; epidermis shaggy at base 

 and posterior end; hinge teeth few In num- 

 ber and feeble; color chestnut brown with 

 white rays near imbones and sometimes ex- 

 tending to margins, these rays visible In- 

 side as well. Length 1-2 Inches. 



In Florida this is a much commoner 

 species than A. Candida. 



PI. 4, Fig. 2 



Cape Hatteras, North Carolina to 



Texas; West Indies 



ARCA CANDIDA Guildlng. Bright Ark. Shell 

 compressed, gaping toward anterior base, 

 posterior end pointed; umbones elevated; 

 surface covered with fairly strong rough 

 irregular growth lines and ridges which 

 give a cancellated and beaded appearance, 

 this sculpture strongest upon the posteri- 

 or slope; epidermis heavy brown and shaggy; 

 teeth indistinct; ground color and interi- 

 or white. Length 2-2.5 Inches. 



The beauty of this shell is en- 

 hanced by the often golden-brown epidermis 

 which is darker at the back of the shell, 

 where it extends like a fringe. Double, 

 fresh shells have been taken at the Yamato 

 rocks, Florida. 



PI. 4, Fig. 3 



North Carolina to the West Indies 



SUBGENUS ACAR Gray 1847 



ARCA RETICULATA Gmelln. Net-work Ark. 

 Shell small. Inflated; posterior ridge end- 

 ing in point at posterior base; strong ra- 

 diating ridges crossing stronger concentric 

 ones, some ridges scaly; hinge short, teeth 

 medium; edge of shell toothed; color whit- 

 ish with yellowish-brown epidermis. Length 

 18 mm. often less. 



This species and the following 

 tiive chiefly under sponges and coral rock 

 in shallow water, especially in the south. 

 PI. 3, Fig. 4 



North Carolina to the West Indies 

 and Texas 



ARCA ADAMSI E. A. Smith. Adams Ark. Shell 

 inflated, rovinded In front; hinge and 

 basal line parallel; umbones moderately 

 full, turned forward; teeth few, rather 

 strong. Color whitish or brown. 



This appears very close to the 

 European A. lactea but may be distinguished 

 by the fact that its radial riblets are 

 formed by rows of trailing blisters, or 

 hollow ones, which are very friable and 

 often entirely worn off, leaving the shell 

 smooth. Length 12 mm., height 7.5 mm., 

 diam. 7.5 mm. 



PI. 3, Fig. 3, PI. 76, Pig, 19 

 North Carolina to the West Indies 



GENUS NOETIA Gray 1847 



NOETIA PONDEROSA Say. Ponderous Ark. Shell 

 heavy, swollen; umbones well separated, 

 about two-fifths fronj posterior end; hinge 

 area wide, flat, very dark brown; about 

 thirty- two radiating flattened ribs; close- 

 set undulating concentric sculpture, strong- 

 est between and becoming obsolete on the 

 ribs, weaker toward the umbones; ground 

 color yellowish white, dark brown shaggy 

 epidermis most persistent toward lower mar- 

 gin; interior yellowish white in center, 

 dull, becoming white and glossy toward the 

 scalloped edge; hinge teeth numerous, 

 turned backward at posterior end. Length 

 2 Inches. 



Single valves are usually taken up- 

 on the New England beaches. The species 

 is abundant at Sanibel, Florida. 



PI. 4, Fig. 1 



Massachusetts to Florida and Texas 



GENUS GLYCYMERIS Da Costa 1778; 

 Pectunculus Lamarck 1799 

 (BITTER SWEET SHELLS) 



Shell solid, equlvalve, convex, 

 epidermis velvety; hinge wide, curved, bear- 

 ing a series of equal-sized teeth which are 

 faintest under the umbones, arranged fan- 

 shaped; muscular impressions sub-equal; 

 palllal line simple. 



