66 LESSON XII. 



and the inequalities of the surface. Here is a 

 shell called Conus marmoreus : 1 wish you to 

 examine it, and draw out its specific character ; 

 it is considered as the type or representative of 

 the Conus, from its having the characteristics 

 of the genus strongly marked. Now, tell me 

 what you have to do. 



Child. We must try and describe this shell. 



Teacher. Yes ; but you must recollect that 

 you have to point out the specific distinctions 

 only ; you must now omit the generic marks, as 

 you have already determined them, and they are 

 implied in the name Conus. First, what is the 

 size of this Cone? * 



Child. It is rather more than two inches long. 



Teacher. Yes, in length it generally varies 

 from two to three inches. What is the colour 

 of the shell, and that of its markings ? 



Child. The ground is a dark chesnut brown, 

 approaching to black, and the markings are 

 white. 



Teacher. What form do the spots most 

 nearly resemble ? 



Child. They are nearly triangular. 



Teacher. You may call them white subtri- 

 angular spots ; sub means under, and when pre- 

 fixed to an adjective implies that the quality 



* The children should have the length of an inch given 

 to them, and by degrees they will learn to determine the 

 dimensions of the specimens without measuring them. They 

 should also be practised in deciding colours and their various 

 shades, by referring at first to some standard. Werner's 

 Nomenclature of colours is a useful work for this purpose. 



