“ 
402 Miscellanies. 
2. Even to the present time, almost insurmountable difficulties 
exist to the acquisition of characteristic petrifactions, which, in the 
actual state of the science, have become indispensable in a collec- 
tion of rocks, destined for study and teaching. 
3. To lessen these obstacles and supply this need, we will furnish 
collections of rocks and petrifactions, which shall be distinguished by 
their selectness, and the variety of pieces which compose them. 
4. To facilitate their acquisition, they shall be forwarded by par- 
cels every six months—et par le roulage. 
5. Each parcel shall contain from 50 to 60 specimens of rocks 
and petrifactions. 
6. The specimens of rocks shall be from 9 to 12 inches square, 
according to the wish of the subscribers : all shall be well character- 
ized, fresh, and selected with care. That the most important points 
in each formation ma: be presented, the specimens shall not come 
_ from one country, but will exhibit a very great variety in a geo- 
graphical respect. Duplicates and useless varieties will be rejected : 
the subscribers shall receive only those specimens which exhibit the 
essential characters. 
7. As to petrifactions, we propose a double object ; a knowledge 
of their forms, and that of their geological relations ; consequently we 
will furnish them either isolated, or remaining in the rock. We con- 
ceive that the first cannot be exhibited but in’ their natural condition, 
and that it is not always possible to bring the last into a determinate 
form, without depriving them of a part of their characters. 
8. Each specimen shall be accompanied by a printed ticket, ex- 
hibiting the German, French and English nathes. They will indi- 
cate, moreover, with more or less of detail, the known position of the 
object, and its localities. Lest the tickets should be too long, the 
most obvious characters will not be described. The labels of the 
rocks will be prepared under the direction of Counsellor and Pro- 
fessor Leonhard ; those of the petrifactions will be the work of Pro- 
fessor Bronn, 
9. As far as possible, each parcel shall present examples of all the 
principal formations and petrifactions, so that they can be immediate- 
ly arranged according to the systems of Humboldt, Boué or Refers- 
tein. The last parcel will be accompanied by an accurate catalogue 
of the entire collection, which will consist of eight or ten parcels, 
