TO GEOLOGY. 149 



Observations. This beautiful species differs from those 

 above described, in having shorter folds and in being 

 covered with minute striae, which are alternately larger 

 and smaller, and resemble the finest lines of the graver. 



F. acutus. Plate 5. Fig. 153. 



Description. Shell subfusiform, furnished with large 

 longitudinal folds on the middle of the whorl, closely 

 covered with transverse alternate striae ; substance of the 

 shell thin ; spire rather elevated, acutely pointed ; whorls 

 seven, subangular ; canal rather short, much curved ; 

 mouth subrotund ; outer lip sharp. 



Length .6, Breadth 5-20ths, of an inch. 



Observations. In general outline it resembles the last 

 described, but may be distinguished at once by the trans- 

 verse striae, which in this are not so fine. The canal is 

 much more curved. 



F. Conybearii.* Plate 5. Fig. 154. 



Description. Shell subfusiform, furnished with longitu- 

 dinal folds cut by rather large transverse striae ; substance 

 of the shell rather thick ; spire somewhat elevated, point- 

 ed ; whorls six ; canal rather short, oblique ; mouth sub- 

 . ovate ; outer lip thickened, within crenate. 



Length .4, Breadth .2, of an inch. 



Observations. This species resembles the two last. It 



* Named after one of the distinguished authors of the " Outlines of 

 the Geology of England and Wales," the Rev. Mr Conybeare. 



