CONUS CONE. 5P 



the edge of the lips has any of the liquid run 

 over? 



Child. No ; the shell holds the water like a 

 cup. 



Teacher. When this is the case, the mouth is 

 said to be contracted. But observe what is the 

 consequence when I attempt to fill a Cone with 

 water up to the lips. 



Child. The water runs out before it reaches 

 the lips. 



Teacher. Examine where the liquid flows out, 

 and what is the cause of this difference in the two 

 shells. 



Child. The water flows out, at the base of 

 the cone. In the other shell the lips are united ; 

 in the cone they are separated by a small channel. 



Teacher. This channel is called a sinus, from 

 the Latin sinus, a curved line. If the two lips 

 be separated by a sinus, liquid poured in overflows 

 before it reaches the lips ; the aperture in this 

 case is called effuse, from the Latin fus us, which 

 signifies poured out. You have no doubt heard 

 the term effusion applied to the overflowing of any 

 liquid ; you will now understand what such an ex- 

 pression means. Compare the columellar lip of 

 the Cone with the corresponding part in these 

 shells (a Voluta and a Cyprsea) and describe it. 



Child. It is smooth. 



Teacher. Examine all your Cones, and see 

 whether they are all quite smooth. 



Child. No : there are stripes at the base of 

 some of them. 



