16 BOOK OF SPECIES. 



BULLA. 



Involute, without a columella ; spire but slightly, if 

 at all, exserted ; outer margin acute ; aperture 

 ^extending the whole length of the shell. 



B. LiGNARTA. Oblong^ looscly convoluted, 

 attenuated towards the spire, transversely striated, 

 pale tawny, thin, semi-transparent; spire trun- 

 cated and umbilicated. B. 2^ W. 18. 20. 



B. AMPULLA. Roundish opaque, cinereous, 

 dotted in waves, and marked with various shades 

 and spots of reddish brown ; apex umbilicated. 

 2...1i. W. 18. 18. 



B. STRIATA. Oval-oblong, opaque, dotted 

 in brown waves, cinereous, striated at the base ; 

 outer lip contracted in the middle ; apex umbili- 

 cated ; in colour resembles the last, but is smaller 

 and longer in shape. W. 18. 19. 



B. PHYSis. Rounded, very smooth, pellucid, 

 with waved brown transverse stripes, more or less 

 crowded; aperture large; spire depressed. \l 

 ...1. W. 18. 24. 



B. FASciATA. Sub-globose, thin, pellucid, 

 whitish ash-colour, with four transverse brown 

 bands, of which two on the middle of the back 

 enclose between them a white one, and the others 

 are placed at the extremities of the shell ; longi- 

 tudinal striae most slender, if. W. 18. 2/. 



