348 Fossil Shells, are all of Species now extinct. 
The method of finding the triple square in the first row of any 
period independent of an additional operation, wes suggested to 
me by a Mr. Holdred, who is now about to publish a small tract, 
in which he has shown by an original and ingenious method, 
how the roots of equations as well as the roots of numbers may 
be accurately and easily extracted by one method which is not 
an approximation, but as direct as the rule for division or those 
employed in the extraction of roots can be. His principle ap- 
pears to be new, and it is more general than any thing of the 
kind that has yet appeared in this country. 
LVI. An alphabetical Arrangement of the Places from whence 
Fossil Shells have been obtained by Mr. James SowERBY, 
and drawn and described in Vol. \l. of his * Mineral Con- 
chology,” with the geographical and stratigraphical Situa- 
tions of those Places, the Species and Varieties of Fossil Shells, 
Sc. By Mr. Joun Farry Sen., Mineral Surveyor. 
To Mr. Tilloch. 
Sir, — Mg. SoweErsy in June last completed a second volume 
of his excellent work, entitled “ Mineral Conchology,” contain- 
ing 101 coloured Plates, of the Shells of formerly existing Fish, 
which have been found imbedded in the British Strata, with one 
or two exceptions, as to Shells found near the opposite coast of 
France; and in which volume he has given the names and de- 
scriptions, of 184 species of such Fossil Shells, that were widely 
distributed through the British series of Strata; yet all of them 
prove perfectly distinct from any Species of the Shells of ana- 
logous living Fish, in any known part of the World! which 
last, further confirms, if any confirmation were at this day want- - 
ing, what that experienced and enlightened naturalist Sir Joseph 
Banks has, uniformly and for many years past been often heard 
to say, as to every Shell found imbedded in the Strata, which he 
had seen, being of an extinct species ! 
Besides the above number of Fossil Shells described and xamed 
in this volume, Mr. Sowerby has therein described 5 Varieties, 
of as many species of these Shells, and has distinguished them 
by the addition of 8, after their specific names: in like manner, 
I have ventured, ina Stratigraphical Index, which I have sent to 
Mr. 8. (to be printed and accompany his 2nd volume) affixed 
Greek Letters, 6, y, @, &c. to distinguish 33 other Varieties of 
these Shells, which, by the Places mentioned, and other circum- 
stances connected therewith, and mostly also, by what is said and 
shown of the Shells themselves, appear to ine to be different 
Species, and belonging to different Strata, from the Shells and 
Habitats 
‘ 
