DON ACID AE 437 



A bra aequalis Say Common Atlantic Abra 



Plate 30V 



North Carolina to Texas and the West Indies. 



1/4 inch in size, orbicular, smooth, glossy and rather inflated. Surface 

 may show a slight iridescence. Periostracum very thin and clear yellowish. 

 Anterior margin of right valve grooved. A very abundant and very simple- 

 looking bivalve. Compare with lioica. 



Abra lioica Dall Dall's Little Abra 



Plate 3o\v 



Cape Cod to south Florida and the West Indies. 



M inch in size, similar to aequalis, but the beaks are nearer the anterior 

 end, the shell is thinner, and more elongate. Anterior margin of right valve 

 not grooved. The prodissoconch at the beaks is large, tan and more trigonal 

 in shape than the adult. Common from 6 to 200 fathoms. 



Family DONACIDAE 

 Genus Donax Linne 1758 



The posterior end is the shortest and the fattest. 2 cardinal and an ante- 

 rior and a posterior lateral in each valve. Pallial sinus deep. 



Donax variabilis Say Coquina Shell 



Plate 3or 



Virginia to south Florida and Texas. 



V2 to % inch in length. Ventral margin of the valves straight and almost 

 parallel with the dorsal margin. The thinner, anterior end is commonly 

 smooth, but may be microscopically scratched with radial Unes. From the 

 middle of the valve to the blunt posterior end, small radial threads appear 

 which become increasingly larger posteriorly. Internal margin of valves 

 minutely denticulate. Color variable and commonly very bright, especially 

 inside: white, yellow, pink, purple, bluish, mauve and commonly with rays 

 of darker shades. 



The subspecies roemeri Philippi (pi. 3oq) is very common along the 

 Texas shores. The posterior end is blunter, the whole shell not so elongate, 

 and the ventral margin sags down. 



Donax fossor Say Fossor Donax 



Long Island, New York, to Cape iVIay, New Jersey. 



Never exceeds Vo inch in length, very similar to variabilis, but almost 



