16 
have red blood, an exception to the rule that the blood of 
mollusks is colorless. From this peculiarity Area is some- 
times called the “bloody clam.” 
An Arca not often found in good condition on our coast is 
Arca transversa Say, (Fig. 9). This is an oblong shell, 
sculptured with about twenty-five squarish riblets. The brown 
epidermis is generally lacking on specimens washed up on the 
beach. 
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Fig. ro. Arca pexata. 
Another species often found all along the Jersey coast is 
Arca pexata Say. It is more rounded than the other species, 
and the comb-toothed hinge-line is more curved. It has about 
thirty-two radiating riblets, and when fresh is covered with a 
dark epidermis which is hairy in the grooves between the ribs. 
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