284 M. Brongniart's Observations 07i some 



very places which contain these vegetable remains, allow me 

 now to do away with this error, and will shew how much one is 

 exposed, in this sort of study, to the danger of subdividing unne- 

 cessarily, by considering as distinct species the different portions 

 of the same plant. 



The genus of fossil plants to which Count Sternberg has given 

 the name of Syringodendron, contains stems, the surface of which 

 is covered with numerous parallel, and very regular, convex 

 ribs. On the middle of the ribs are placed in quincunx order, 

 simple or double lines, or rounded impressions, which are always, 

 however, very small, and never have the form of a disk or 

 shield, as in the genus Sigillaria. This character alone would 

 distinguish these two genera, but it would further appear of 

 great importance, inasmuch as it announces a great difference in 

 the form of the organs, whose insertion is indicated by these im- 

 pressions. In the Sigillariae, the disks have been regarded; with 

 reason, as the marks left upon the bark by the base of their pe- 

 tioles, after the fall of the leaves. The form of the base of these 

 petioles, and the disposition of the vessels which have traversed it, 

 render it almost certain that these plants have belonged to the 

 family of ferns. The form of the impressions of the Syringo- 

 dendra, indicates, on the contrary, small organs, often in pairs, 

 in which the traces of spines, like those of the cactuses, fleshy 

 Euphorbiae, &c. have been supposed to be recognised. This 

 character has been deemed sufficient by several naturalists to in- 

 duce them to admit the analogy. A perfect similarity of form in 

 the Syringodendra and Sigillariae, and their existence in the same 

 strata of the globe, might have impressed an idea, if not of their 

 identity, at least of their mutual resemblance ; yet these two 

 genera have been admitted as distinct by all modern authors. 

 Direct observation, however, comes to prove, that they are only 

 two parts of one and the same plant ; that the genus Syringo- 

 dendron must be erased from the list of plants ; 'and, in a word, 

 that the alleged species of this genus are nothing else than Si- 

 gillariae deprived of their outer bark. Several specimens collect- 

 ed in the mines of Valenciennes, Mons, and Charleroi, evidently 

 prove this identity ; they are either Sigillariae or Syringodendra, 

 according as the carbonized bark which envelopes the stony 



