CONUS CONE. 57 



LESSON IX. 

 GENUS. CONUS. 



THE party should have before them a variety 

 of univalve shells, among which there should 

 be a large proportion of such cones as have the 

 characteristics of the genus well defined.* 



Teacher. I have brought a variety of shells 

 for you to examine ; what is the point of resem- 

 blance which unites them all in one class ? 



Child. They are all composed of one valve ; 

 they are all univalves. 



Teacher. From these univalve shells select 

 those which appear to you to be similar in their 

 general appearance, and in the form of their 

 mouths. 



Child. We have done so. 



Teacher. Explain to me what you have done. 



Child. We have selected those shells which 

 have the same general appearance, and a similar 

 kind of mouth. 



Teacher. What was the common point of 

 resemblance in all the shells which I have set 

 before you? 



Child. Their being composed of only one 

 valve. 



* It is very important in teaching children to draw out the generic 

 character of shells, to set before them specimens in which the dis- 

 tinguishing features are strongly and clearly marked ; their ideas 

 will then be distinct, vivid, and permanent. After this they may 

 proceed to the examination of shells, which, combining the qualities 

 ol different genera, form the connecting links between them. 



