410 Dr. Senry Woodivard — On Pleurotoma prisca. 



the posterior margins, round the sutural edges of which last run 

 three or four fine, threadlike, raised lines, occasionally replaced by 

 two or three shallow, obscure furrows ; the last whorl is nearly 

 conical, obscurely sulcated at the base and deeply notched at the 

 extremity ; the anterior canal is wide, very short, and indistinct. 

 The aperture is narrow and of an oblong-oval form ; the outer lip 

 wing-shaped, projecting towards the front, thin and sharp on the 

 edge, and smooth within ; the sinus, which is in the very front of 

 the margin, is wide, moderately deep, somewhat triangular in form, 

 and widely rounded at the extremity ; the inner lip is much 

 thickened, and is produced and bent outwards in front, giving an 

 umbilicated appearance to the columella, which is slightly twisted 

 and prominently crested towards the base." 



P&wroioma ^nsca, Solander, sp. Middle Eocene : Barton, Hants. 

 (Drawn of the natural size.) 



There are five specimens figured in Edwards' & Wood's mono- 

 graph, on tab. xxxiii, figs, la-e ; the largest, a and d, being from 

 Barton, and measuring 70 and 74 mm. respectively in length, by 

 25 and 22 mm. in breadth. 



Mr. Beadnell's specimen measures 90 mm. in length and 28 mm. 

 in breadth, and is therefore considerably larger than either of the 

 above examples. When, however, we turn to other Eocene species 

 of Pleurotoma, we find PL cochlis attaining to a length of 80 mm., 



