X INTRODUCTION. 



The Professor promised at the conclusion of his paper to continue the sub- 

 ject, by considering the plants which occur in the brown coal formation, which 

 he considers as of much later origin than those mentioned in his present essay, in 

 which he has confined himself to the plants found in the black coal formation. 



M. Adolphe Brongniart, the son of the very eminent mineralogist, who is 

 nt the head of the French Royal Manufactory of Porcelain at Sevres, has given 

 the following classification of fossil plants, in his Essay " Sur la Classification 

 et la Distribution de Vegetaux Fossiles," inserted in the "Memoires du 

 Museum D'Histoire Naturelle," and also printed separately in quarto, Paris, 

 18 c >2 : 



Class 1 . Stems whose internal organization is recognizable. 



1. Exogenites. Wood formed of regular concentric layers. 



2. Endogenites. Wood composed of insulated bundles of vessels which are 



more numerous towards the circumference than at the centre. 



Class 2. Stems whose internal organization is no longer distinct, but which 

 are characterized by their external form. 



3. Culmites. Stem jointed, smooth ; a single impression at each articulation. 3 



4. Calamites. Stem jointed, regularly striated ; impressions rounded, small, 



numerous, forming a ring round each articulation, or sometimes 

 wanting. b 



5. Syrincodendron. Stem channelled, not jointed ; impressions dot-like or 



linear, arranged in quincunx. 



6. Sigillaria. Stem channelled, not jointed ; impressions in the form of 



disks arranged in quincunx. 



7. Clathraria. Stem neither channelled, nor jointed ; impressions in the 



form of rounded disks, disposed in quincunx. d 



* These stems appear to M. Brongniart to belong to the arborescent grasses, to calamus or its allied 

 genera. 



b M. de Candolle suggested to M. Brongniart that these stems appear to belong to some plants of the 

 natural order of equisetaceae. 



M. Brongniart considers these remains to belong to genera which are entirely extinct. 

 1 M. Brongniart shews in his paper the great agreement between these two genera, and the stems of 

 ferns in every respect, excepting magnitude, and considers them as evidently owing their origin to plants 

 of that natural order rather than to the palms. 



