342 INTRODUCTION TO CONCHOLOGY. 



species delight to burrow in the sand, or among loose 

 pebbles on the sea-shore, and are found in almost every part 

 of the known world. 



The Cajftsa, which is closely allied to Bonax, may be 

 described as transverse, equivalve, somewhat inequilateral, 

 with the valves closed, and never crenulated round the 

 inner margin, which occurs in Bonax. Tlie hinge is com- 

 posed of two cardinal teeth in one valve, and one cardinal, 

 with two nearly obsolete lateral teeth, in the other. The 

 ligament is external, and the muscular impression of the 

 mantle exhibits a large oblong sinus. 



Family XIII. Lithophaga. 



Ye dwell iu rocks, strange creatures as ye are. 



Shunning the light of day, and boring deep. 



To make your homes ; then, looking forth at will. 



Ye watch, the wold waves as they come and go. 



Nor heed the fierce north wind, though howling loud 



Around the old sea-wall, or rock, or cliif, 



^Yhere you are stationed. 



Lamarck instituted this family for the purpose of asso- 

 ciating a small group of terebrating moUusks, which, 

 although inhabiting hard calcareous rocks, differ from the 

 Tuhicola and FJioladaria, not only in the growth of their 



