MOLLUSKS 



125 



Fit;. Sj; LITTLE-NECK CLAM. Long 

 Island Sound. 



The Round Clam, Quahaug, or Little-neck Clam, fVemis mer- 

 cenaria, Fig. S3J, is the common hard-shelled clam of the New- 

 York market, and the fishery in the Middle Atlantic States is worth 

 $200,000 annually. The Indians 

 made their purple wampum from 

 its shell. 



The hard clam ranges from 

 Yucatan to Nova Scotia, but is 

 common only from the Carolinas 

 to Cape Cod. It is most abund- 

 ant in shallow bays and estu- 

 aries where it lives below the 

 level of low tide. 



It is often seen lying upon 

 the bottom, but is able to bur- 

 row to a slight depth by means of 

 its strong muscular foot which 

 can be protruded from the shell 

 so as to sweep backwards and 

 forwards over a wide area. The siphon is short and blunt, and the 

 end displaying the two openings is forked. A continuous current 

 of water flows in tlirough the lower opening, and out through the 

 opening nearest the hinge of the shell. The mantle edge around 

 the lip of the valves is crumpled. The shell is covered by a graj'ish 

 or dull brownish-gray skin, and it displays quite regular and deep 

 rings of growth. The siphon is light yellow, while the foot is 

 white. Kellogg finds that these clams grow very rapidly, and 

 may become about three and a quarter times their former volume 

 in six months. These clams feed upon diatoms and minute organ- 

 isms, which are drawn into the gill chamber through the in-current 

 tube of the siphon. The particles serving as food are collected by 

 the slime upon the gills, and driven into the mouth by the motion 

 of the cilia, while undesirable material is thrown upon the surface 

 of the body or the mantle and then driven to the base of the in- 

 current opening of the siphon, where it ma}' be discharged by a 

 sudden closure of the valves of the shell. 



The Razor Clam, (Ensis antej-icana, Fig. S4). This curious 

 clam resembles in shape the handle of a razor, and is found from 



