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 may 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 ; consequendy 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 names. 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, Boue 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. 



