UNIVALVE MOLLUSCANS. 273 



blematical : probably intermediate species will 

 come to light which will render this point 

 more evident than the shell of these animals 

 appears to indicate. 



With regard to their functions and the part 

 assigned to them in the great plan of creation, 

 little is known ; probably, from their numbers in 

 some parts, they may help to soften the rocks, 

 so that they may, at some destined hour, yield 

 more readily to the force of the winds and waves; 

 thus they may be enumerated amongst the in- 

 struments which the Creator employs to effect 

 his purposes, and such changes in the coast of 

 any country, as he wills shall take place. 



They afford a beautiful instance of the gradual 

 progress of Creative Wisdom from form to form. 

 If the student of the tribe looks with inquiring 

 eye at a collection of the Patellidans, or limpets, 

 in the flattest and most depressed of them 1 he will 

 find no small resemblance to one of the valves of 

 a bivalve shell, he will soon, however, discover a 

 prominence in it, the first tendency towards the 

 spiral convolution, a little removed from its cen- 

 tre, which will prove to him that it belongs to a 

 very different tribe ; looking again at others that 

 are more elevated and conical, 2 he will see the 

 same prominence or beak forming a more strik- 

 ing feature, and ascertaining these shells to be 

 univalves, he will find, upon a comparison of 



1 Umbrella indica. 2 Patella vulgata. 



VOL. I. T 



