Fig. 306.—Strombus luhuanus. Fig. 307-—Strombuscan- Fig. 308.—Strombus thersites (Gray). 
(Linnzus). cellatus. (Lamarck), 
Fig. 309,—Pteroceras scorpio Fig. 310.—Pteroceras millepeda 
(Linnzus). (Linnzus). 
from those of Strombus chiefly in this, that the right edge develops 
itself with age into long and slender digital spines more or less 
numerous, the numbers of which vary according to the species. The 
