SHELLS. 29 



termine that they are shells ; but more than this, 

 do you not observe that some are more alike than 

 others ? 



Child. There are some that are very much 

 alike in shape. 



Teacher. Yes, and yet differ in other respects ; 

 but is this all that you observe ? 



Child. No, there are some that appear exactly 

 alike. 



Teacher. Thus when you look at a collection 

 of shells for the first time, you are struck by their 

 general similarity, and you at once call them all 

 shells. After a little inspection, it will be evident 

 that amongst them, some have a few points of 

 resemblance, and that others are quite alike in all 

 respects. Thus you begin to perceive that the 

 variety which at first almost bewildered you, is 

 limited by a principle, and whilst your eye is gra- 

 tified by the diversity, your judgment is satisfied 

 by the order you find preserved . Tell me a simi- 

 lar circumstance in another class of natural objects. 



Child. Flowers afford one. All roses are 

 alike in general appearance, but the Moss Rose 

 is easily distinguished from the China Rose. 



Teacher. The variety exhibited in the works 

 of nature cannot fail to delight us, and the resem- 

 blances observable in them enable us to classify 

 and arrange them. There is still one point with 

 respect to shells which we have not considered ; 

 I mean the situations which they occupy. Where 

 are shells found ? 



