50 RAMBLES OF 



NO. HI. 



In moving along the borders of the stream, we may 

 observe, where the sand or mud is fine and settled, a sort 

 of mark or cutting, as if an edged instrument 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 con- 

 siderable size, which is tenanted by a molluscous animal 

 of singular construction. 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 species 

 are found in the same situations, which, externally, are 

 rough and inelegant, but within are ornamented 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 apparatus for respiration, formed of a network 

 regularly arranged, of the most exquisitely delicate tex- 



