INTRODUCTION. 
WHEN a widely extended knowledge of the ever-varying forms 
of animal life had compelled the student of zoology to augment 
the generic groups on a similar scale of magnitude, amid the 
shock of contending systems, many interesting species, pre- 
viously well known to the older naturalists, sunk into obscurity. 
The revolution accomplished, and the last feeble defenders of 
a system, which Linneus himself would have been the first to 
modify in conformity with the enlarged views which an increased 
acquaintance with natural objects would have produced, being 
silenced, if not convinced, attention was again directed to those 
almost forgotten shells which the followers of the French 
school of Conchology had omitted to cite in illustration of 
their genera. Deshayes, in France, and Gray, in England, 
were the foremost in the field; and to their profound know- 
ledge of the writings of their predecessors is due the rescue of 
many a half-forgotten shell from the oblivion into which it was 
falling, and the restoration of their original names to many of 
the species published by the old German authors. The just 
and enlightened views entertained by these truly erudite natu- 
ralists have kindled so widely spread a spirit of research, that 
the species of Born, Spengler, Chemnitz, Schréter, Martyn, 
Gronovius, and other less notable conchologists, will ere long 
be catalogued under their new generic appellations. Until this 
shall be definitively accomplished, the continual shifting of 
names, from the preoccupation of specific epithets, will entail a 
serious and never-ending toil wpon all who respect the rights of 
priority, and will burden the memory with a chaotic mass of 
synonyms. Since, then, by almost universal agreement, the 
publication of the tenth edition of the ‘ Systema Nature’ (that 
B 
