54 BIVALVES. OSTREA, 



The exterior of the shells, as has been before observed, 

 is usually covered with elevated longitudinal ribs and 

 grooves, which are variously diversified with beautiful 

 colors and fine chequer- work. The ribs are mostly co- 

 vered with undulated and transverse strise, not unfre- 

 quently assuming the appearance of elevated scales, as 

 in the O. imbricata and O. dubia. In others, again, the 

 strise are crenated, as in the O. radula; and some, as the 

 O. nodosa, &c. have large knobs or tubercles raised upon 

 the ribs. The margins of the interior of the Ostreae are 

 generally crenated, and often beautifully colored. 



The hinge is universally without teeth, and furnished 

 with an ovate hollow; in the vicinity of which are placed 

 lateral transverse grooves, running in a parallel direction 

 in both valves, but not locking into each other, as in the 

 genus Area. 



The common scallop, O. maxfma, is found in most Eu- 

 ropean seas, in large beds, from which they are dredged 

 by the fishermen, and afterwards pickled and barrelled 

 for sale: in some instances, also, they are brought to mar- 

 ket in the state they are caught, and are eaten fresh. 

 These shells were formerly worn by pilgrims, on their 

 hat or coat, as a mark of their having crossed the sea, for 

 the purpose of paying their devotions at the holy shrine, 

 in Palestine: in commemoration of which, they are still 

 preserved in the armorial bearings of many families of dis- 

 tinction. 



The scallops arc found harbouring among fuci and zo- 

 ophites : they have the faculty of leaping out of the water, 

 and are enabled to effect a very rapid motion, by open- 

 ing and closing their valves. 



The second division of Ostreae consists of those which 

 in construction, substance, and coloring, are more nearly 



