SUPPLEMENTARY INDEX TO VOL. II. 244 
Where dots are used in the above list, in the place of 
the specific or trivial name, reference is intended, to these 
species, which, although not named by Mr. Smith in his 
Strat. Syst. are by his references therein, deseribed, as 
being of the same species, in two or more strata; and in 
parenthesis I have added, the first of his pages, in which _ 
each of such shells occur. 
For an early number of the “ Philosophical Magazine,” 
it is my intention to communicate to Mr. Tilloch, the 
particulars of the strata and places, of each of the above 
279 shells, with references to Min. Conch. and to Mr. 
Smith’s two works on fossil shells; and I intend to ac- 
company the same by a few general remarks, as to the 
great use and importance of fossil shells, in untheoretical 
and useful geology. I am extremely desirous of calling 
the attention of your Readers, and of requesting them 
to contribute all they can, in the way of additional speci- 
mens, and more precise localities, &c.* from the former 
and from new places of the shells in the above list, 
particularly the Ammonites, Terebratula, Ostrea and 
Gryphites, Cardita? Trigonia, Plagiostoma, Unio, Pec- 
ten, &c. 
I have prepared, and shall in a few days send to Mr. 
Tilloch, (as I did on the conclusion of your first volume,) 
a List of the Piaces, alphabetically arranged, and their 
situations, from whence the shells described in Vol. II. 
are mentioned to have been obtained, the stratum at each 
* Where several species or varieties of shells occur in thesinking of any 
particular quarry, well, pit, &c. or in the face of any cliff or bank, it 
would be of vast importance to know, their relative places and heights 
above each other; because this order will be found invariable, in different 
places, after making allowance for those particular species, which were the 
cotemporaries of one or more shorter lived species. 
