162 THE ELEMENTS 



Retundated, blunted, or turned at 



the edge. 

 Reversed spire, is when the volutions 



are the reverse way of a common 



cork screw. 

 Reversed spires, when the spires are 



turned upwards. 

 Revolute, rolled backwards. 

 Ribbed, longitudinal, and sometimes 



transverse ridges. 

 Ridge, the upper part of a slope. 

 Rima, the interstice between the valves, 



when the hymen is removed. 

 Rostrated, having a beak ; the exten- 

 sion of the shell, in which the canal 



is situated. 

 Rotund, round, circular, spherical. 

 Rudiment, the first part of a thing ; 



generally applied to the indistinct 



teeth of shells. 

 Rufous, of a reddish colour. 

 Rugose, rugged, full of wrinkles. 



