M. Alex. Brongniart sur les caracteres Zoologiques, Gc. 213. 
Javas, such as the shining black lavas inclosing brilliant 
white plates of feldspar, and a profusion of deep black crys- 
tals of pyroxene, and those of Licatia inclosing the same 
minerals, and large greenish crystals of chrysolite surround- 
ed by minute grains of the same, have nothing analogous in 
any ofthe superficial rocks of Sicily—the Abbe F. suppo- 
ses that all the lavas of Sicily are derived from primitive 
rocks which extend from the mountains of Pelorus under 
Etna and the extinct volcanoes; that the ancient lavas 
are formed from the upper and less compound strata of 
these rocks, and that the modern crystalline lavas are 
brought up from greater depths where the rocks are more 
compound and stored with minerals which are not found in 
the upper strataa—The ancient lavas around the base of 
A&itna, such as the rocks of Molta and those of the cyclops 
are as simple as those of the extinct volcanoes of Val di 
Noto, and were probably of the same period. 
Besides these minerals, which compose the paste of 
the lavas, there are others found in the fissures and cay- 
ities of the recent lavas deposited by the condensed va- 
pours. These are muriate of Ammonia, very abundant, 
collected as an article of commerce —several other muri- 
ates, particularly those of soda and iron ; carbonate of so- 
da and Fer oligiste in brilliant scales, and plates lining the 
cavities and implanted in groups upon the surface of the 
lavas.—In the ancient lavas of Val di Noto and the base 
of AXtna, such as the mountains of Paterno, and the rocks 
of the cyclops—various minerals are found deposited in 
the cavities by infiltration, viz. carbonate of lime crystalli- 
zed, zeolite and analcime (cyclopite. Ferr.) 
* 
—————————— eee 
Art. Il.—Analysis of a Memoir, “ Sur les Caracteres Zoo- 
logiques des Formations, uvec Vapplication de ces carac- 
teres & la determination, de quelques terrains de CRAlE ; 
Par Alexandre Brongniart.” (Ann. des Mines, 1821.) 
By J. G. Percivan. 
Tuer design of this Memoir is to establish the relative 
value of geological and mineralogical characters in deter- 
mining the contemporaniely of formations particularly in 
reference to certain formations of chalk. The particular 
