46 LESSON IX. 



be subulate,* from the Latin subul a, a pointed 

 tool. The term spire is now applied to any 

 form resembling that produced by whorls, which 

 rising one out of the other, and decreasing in 

 diameter, though it be not occasioned by whorls. 

 You can, perhaps, recollect an instance in 

 architecture, in which the name is so applied. 



Child. The spire of a church. 



Teacher. When the spire of a shell is 

 formed by whorls, which is generally the case, 

 it is said to be spirally convoluted, the latter 

 term is derived from the Latin words, con to- 

 gether, and volut us rolled. Now examine the 

 spire still more attentively, and you will find 

 some other parts. 



Child. There is a line formed where the 

 whorls meet ; has this line any particular name ? 



Teacher. Yes, it is called the suture, from 

 the Latin sutura, a seam or joining; do you 

 perceive any difference in the sutures ? 



Child. Yes, in some shells it is quite a ridge, 

 and in others it is more like a channel. 



Teacher. When it is raised like a ridge or 

 keel, it is called carinate, from the Latin carin a, 

 a keel ; when it is a sunken line, it is said to be 

 channelled. Now look at your shells again. 



Child. Are any parts of the shell considered 

 to be the top and bottom. 



Teacher. Yes, the point of the spire is the top. 

 You recollect what the top and bottom of a cone 



* See Buccinum Subulatum. Plate III. Fig. 4. 



