General Science. SOT 
parts of the Paris formation. The highly important and in- 
teresting geological travels of Beudant, will appear in June, 
and are to be illustrated by two large geognostical maps. 
40. Gerhard on the Chemical formation of compact and gra- 
nular Strata, and of conglomerated Rocks* — Professor Jame- 
son, in various papers in /the public Journals, and in the Me- 
moirs of the Wernerian Society, maintains the chemical for- 
mation of strata, whether compact, granular or conglomerated. 
This mode of formation is not peculiar to rocks of the primitive 
class, but extends to the transition and secondary classes, many 
of the members of which, whether they appear in vast imbed- 
ed masses, like granite and porphyry, or in beds or veins, Pro- 
fessor Jameson considers as chemical and cotemporaneous in the 
formation. Gerhafd, in the Memoirs of the Boyal Academy 
of Berlin, for 1819, advocates the same opinion, and it has been 
extensively employed by Dr Hibbert in his account of the Shet- 
land Islands, published in this Journal. We shall in our next 
number sta;te Gerhard’s views. 
41. Clmrpentier'’s Geognosy of the Pyrenees. — Charpentier 
the younger, an eleve of the Wernerian school, who has already 
distinguished himself by his geognostical investigations, has in the 
press a complete account of the geognosy of the Pyrenees. We 
are informed that this work is distinguished by its excellent ar- 
rangement, accurate descriptions, legitimate inferences, and 
the new and important facts with which it abounds. 
IV. GENERAL SCIENCE. 
42. New Membrane in the Human Eye. — Dr Jacob of Dub- 
lin has recently discovered a new membrane in the human eye, 
of the same nature as that which lines serous cavities, and co- 
vering the retina from the optic nerve to the ciliary processes. 
In the sheep, ox, and horse, or any other individual of the 
Class Mammalia, it presents the same character as in Man, but 
is not so much tinged by the black pigment. In the bird, it 
presents a rich yellow-brown tint. In fishes, where it has 
already been incorrectly described by Haller and Cuvier as the 
medullary layer, it is of a soft, friable, thick, gluey structure, 
its inner surface is not tinged with black pigment, but presents 
