NOMENCLATURE. 23 



spiralis. Spiral ; so twisted that an imaginary 

 plane passing through the middle of the 

 outer whorl shall bisect all the others, or 

 divide them into two equal parts. 



turrita. Turreted ; the whorls gradually attenu- 

 ating or decreasing in the form of a cone ; 

 the length of these shells always consider- 

 ably exceeds their width. 



turbinata. Turbinate ; the belly swelling or tu- 

 mid ; the spire comparatively small, rising 

 as it were from the hollow of the body. 



umhilicata. Umbilicate ; possessing an umbili- 

 cus. 



Varices. Varices; longitudinal gibbous su- 

 tures formed in the growth of the shell 

 at certain proportionable distances on the 

 whorls. 



continuati. Continuous ; running through all the 

 whorls. 



decussati. Decussate ; longitudinally and trans- 

 versely divided or crossed. 



scrobiculati. Scrobiculate ; engraven with cavi- 

 ties towards the margins. 



