CONUS CONE. 61 



Child. No; we observe also their position 

 and direction. 



Teacher. You remember the usual position 

 of the aperture. . 



Child. It is almost always dextral, or on the 

 right side of the shell. 



Teacher. And as this is its usual position, it 

 is not noticed in the generic character ; indeed, 

 the peculiarity of a sinistral aperture never runs 

 through a whole genus of shells. But what do 

 you observe with regard to the direction which 

 the mouth of the cone takes ? 



Child. It is in the direction of a line passing 

 from the apex to the base, that is the length of 

 the shell. 



Teacher. And what do you call the direction 

 of a line passing from the top of a body to its 

 base? 



Child. Longitudinal; the aperture of the 

 cone is longitudinal. 



Teacher. You recollect learning in a former 

 lesson the proper term for shells with a beak, 

 and also for those without one. 



Child. Yes, those with beaks are called 

 canaliculated, and those without entire. The 

 mouth of the cone is entire. 



Teacher. Yes. A litttle experiment will lead 

 you to detect another characteristic of this genus. 

 Observe, I fill this shell (a Turbo) with water to 

 the edge of the lips has any of the liquid run 

 over? 



Child. No ; the shell holds the water like a 

 cup. 



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