MOLLUSCA. 31 



an animal substance called gelatine: the covering 

 of insects is a phosphate of lime. The substance 

 of shells is testaceous, having the hardness of 

 baked earthenware, in Latin, test a; and hence 

 the mollusca enclosed in them are called testa- 

 ceous mollusca: the covering of insects is crus- 

 taceous, having the hardness of crust, in Latin, 

 crust a. 



Child. But whence is the carbonate of lime, 

 of which shells are composed, obtained? Is it 

 found in the sea? 



Teacher. It exudes from the skin of the 

 animal, which, as I told you, is furnished with 

 numerous glands. In these is secreted the cal- 

 cereous matter. 



Child. How very wonderful that they should 

 thus be provided with materials to make their 

 abode ; but how is the shell formed from this 

 substance"? 



Teacher. The little animal you formerly 

 despised is its own architect, and constructs a 

 dwelling exactly suited to its wants. One of our 

 divines, who has written a volume to show that 

 the works of creation are alone sufficient to 

 prove the existence of a wise and beneficent 

 God, says, speaking of a shell, " I do not know 

 whether weight being given, art can produce so 

 strong a case as some shells."* 



What do you now think of the workmanship 

 of these little creatures 1 



Child. It is very wonderful, how remarkable 



Paley's Natural Theology. 



