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. yigNarta. Oblong, loosely convoluted, 
attenuated towards the spire, transversely striated, 
pale tawny, thin, semi-transparent; spire trun- 
cated and umbilicated. B.23. W. 18. 20. 
B. amMpuuLLa. Roundish opaque, cinereous, 
dotted in waves, and marked with various shades 
and spots of reddish brown; apex umbilicated. 
eet.  W. 43. 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. puysis. Rounded, very smooth, pellucid, 
with waved brown transverse stripes, more or less 
crowded; aperture large; spire depressed. 13 
ina WV. a8: A: 
B. rasciata. 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 striz most slender. 14. W. 18. 27. 
