398 
M. DESIIAYES's TABLES OF SHELLS. 
the species, or because the specimen examined was in rather an imper- 
fect state. 
The specific names of the tertiary fossil shells which have been found 
by M. Deshayes to belong to one period only, and for which he has not 
yet discovered any living analogues, are not given, as their enumeration 
would have required more space than could be allotted to such a subject 
in a treatise on Geology; but their aggregate number is included in the 
subdivisions of the column in the right-hand page headed ' No. of species 
in each genus in the following localities,' and in the supplementary table, 
p. 46. 
