EXPLANATION OF TERMS. 



Rostrated. Having a beak, from rostrum, a beak. 



Refuse. Having the lower whorls of the spire 

 pressed into the body whorl, from re, back 

 and tus us, beaten. 



Reversed. Applied to spiral shells, whose vo- 

 lutions turn in the contrary direction to 

 the generality of shells. If when a shell 

 is placed on its base, with the front facing 

 the person looking at it, the aperture is 

 on the right side of the pillar, the shell 

 is said to be regular or dextral, if the 

 aperture is on the left side of the pillar, 

 it is said to be reversed or sinistral. 



Retractile. Capable of being drawn back ; from 

 re, back, and tract us, drawn. 



Reticulated. Crossed like net work ; from reti- 

 cul urn, a small net. 



Revolute. Rolled back ; from re, back, and 

 volut us, rolled. 



Rugose. Rough or wrinkled ; from rug, a 

 wrinkle. 



Rufous. Of a reddish colour. 



Spire. The upper whorls collectively, from the 

 Greek o-vcip (speir), convolutions gradually 

 increasing in diameter. 



Suture. The circular line of the spire, where 

 one volution meets another ; from sutura, 

 a seam. 



Species. The subdivision of a genus, and dis- 

 tinguished from all others of the genus 



