52 R A M B L E S OF 



No. III. 



IN moving along the borders of the stream, we 

 may observe, where the sand or mud is fine and set- 

 tled, a sort of mark or cutting, as if an edged in- 

 strument had been drawn along, so as to leave behind 

 it a track or groove. At one end of this line, by 

 digging a little into the mud with the hand, you will 

 generally discover a shell of considerable size, which 

 is tenanted by a molluscous animal of singular con- 

 struction. On some occasions, when the mud is 

 washed off from the shell, you will be delighted to 

 observe the beautifully regular dark lines with which 

 its greenish smooth surface is marked. Other spe- 

 cies are found in the same situations, which, exter- 

 nally, are rough and inelegant, but within are orna- 

 mented to a most admirable degree, presenting a 

 smooth surface of the richest pink, crimson, or 

 purple, to which we have nothing of equal elegance 

 to compare it. If the mere shells of these creatures 

 be thus splendid, what shall we say of their internal 

 structure, which, when examined by the microscope, 

 offers a succession of wonders ? The beautiful ap- 

 paratus for respiration, formed of a network regularly 

 arranged, of the most exquisitely delicate texture; 

 the foot, or organ by which the shell is moved for- 

 ward through the mud or water, composed of an 

 expanded spongy extremity, capable of assuming 



