18 BOOK OF SPECIES. 
B. cyLInDRACEA (Pennant). Oblong, elon- 
gated, cylindric, transversely striated, white ; ver- 
tex umbilicated ; aperture suddenly dilated at its 
base; columella flattened; small. B. W. 18. 57. 
B. umprticata (Montagu). Oblong, oval, 
white, involute, minute, rounded, and umbilicated 
at the apex. B.),W. 18.58. 
B. retusa (Montagu). Sub-cylindrical, in- 
voluted, minute, striated longitudinally on the 
upper part; apex truncated and umbilicated ; the 
aperture is most contracted in the middle. B. 
minute. W. 18. 59. 
B. oprusa. Minute, cylindrical, involuted, 
white, opaque, wrinkled longitudinally, and be- 
coming rather narrow towards the apex; spire 
somewhat prominent. B. W. 18. 60. 
LAPLYSIENS. 
LAPLYSIA. 
The animal with a dorsal, subcartilaginous, semi- 
circular shield. 
A. Perersoni. S. 254. 
DOLABELLA. 
Oblong, subarcuated, somewhat shaped like an axe; 
on one side narrowed, thicker, callous, and sub- 
