CHAPTER X: THE SURF CLAMS. HEN CLAMS 



Family MACTRiDy^ 



Shell equivalve, three-cornered, heavy; hinge formed 



by two cardinal teeth with laterals; epidermis thick; siphon 



tubes united, fringed at tip; mantle open in front; foot 

 flattened. 



Genus MACTRA, Linn. 



Shell thick, almost equilateral, anterior hinge tooth V-shaped. 

 Widely distributed chiefly in tropical seas. One hundred and 

 fifty species. 



The surf clams live buried just below the surface of the sand. 

 They extend the finger-like foot to a considerable distance in 

 search of food ; also use it in leaping. Star fishes and whelks are 

 their enemies. They are eaten by man, and collected to feed 

 pigs and to fertilise the soil. 



The Solid Surf Clam (M. soUdissima, Chemn.) is the com- 

 mon "hen clam" of the New England coast. It burrows in sand, 

 from which it is dug at low water with shovels or clam rakes. 

 Reeve says that at high water fishermen go out, poking the 

 bottom with sharp sticks. If a stick by chance goes between 

 the open valves of a clam, it closes at once, and the fisherman 

 draws it up. 



The shell is indeed soUdissima. Lines of growth sculpture 

 the surface. The posterior end is long drawn out. The hinge 

 leans forward. The umbones are prominent. When open, the 

 valves show at the hinge the very large heart-shaped cartilage 

 pit, with long channels in both directions, and blade-like teeth 

 with cross striations. The muscle scars are oval and very 

 large. 



This is the largest bivalve on our Atlantic coast. It is pon- 

 derous, too, but so muscular as to be able to leap, by means of 

 its extensible foot, when escaping from enemies. Among these 



332 



