42 BOOK OF SPECIES. 



five, obliquely striated ; aperture semi-circular ; 

 diam. 1. B. T. 95. 



P. CARiNATUS. Horn-colour, transparent, 

 striated, nearly flat on both sides, with a promi- 

 nent obtuse keel in the middle; diam. f. B. 

 T. 87. 



P. spiRORBis. Whitish, striolate, a little 

 concave on both sides ; outer whorl with a sharp 

 keel in the middle, pale horn-colour ; four or five 

 whorls ; aperture heart-shaped, acute at the top ; 

 diam. i. B. T. 92. 



P. CONTORTUS. Nearly flat above, deeply 

 umbilicate beneath, horn-colour, but generally in- 

 crusted; whorls five, remarkably compact and 

 equal; aperture very narrow, lunate; diam. i. B. 

 T. 96. 



P. HispiDUS. Concave on both sides, with 

 finely raised, hispid, spiral striee ; whorls five ; 

 the first large and rounded, pale horn-colour ; 

 aperture roundish oval, dilated, higher than wide, 

 with the upper angle much produced. J. B. 

 T. 97. 



P. NiTiDus. Orbicular, flattened, keeled at 

 the circumference, umbilicated beneath, diaphan- 

 ous, shining, pale horn-colour ; whorls four ; aper- 

 ture oval, inclining to triangular ; diam. l. B. 

 T. 99. 



P. iMBRiCATUS. Flat above, umbilicate be- 



