RAZOR SHELLS, CLAMS, ETC. 22/ 



on the coast of the Middle States, especiaUy in Dela- 

 ware and Chesapeake Bays. 



Pectens, or Scallops, Figure 430, are also prized for 

 food. Their beautiful shells are known to almost 

 every one, for they are much used in making card- 

 holders, pin-cushions, and other little articles. The 

 Pecten swims rapidly by opening and shutting its 

 valves. 



Sea Mussels, Figure 431, inhabit mud-banks which 

 are uncovered at low water. They multiply rapidly, 

 and grow to their full size in one year. By means of 

 a collection of horny threads, called a hyssus, they at- 

 tach themselves to rocks, or to the ground. 



Pearl Oysters, or Aviculas, Figure 432, have shells 

 yielding the beautiful material called ntothcr-of-pcarl, 

 extensively used for making and ornamenting a great 

 number of useful and beautiful articles. They also 

 yield the oriental pearls. 



TJnios, or River Mussels. 



These Mollusks abound in brooks, rivers, ponds, and 

 fresh-water lakes. They are sometimes called Naiades, 

 and there are very many kinds. It would take several 

 books larger than this one to describe all the kinds 

 found in the United States. A few of the forms of 

 Unios are shown in Figures 435-439. Sometimes 

 beautiful and valuable pearls are found in them. 



Razor Shells, Clams, etc. 



The Razor Shells are very long and smooth. They 

 burrow in the sand, and are good for food. The Com- 

 mon Clam burrows in sand and rriud, and is exten- 

 sively used for food, and for bait for cod. 



