423 



s , 



exact figure of the original surface. That such a change has been 

 produced, and that the cortical part of these plants was much 

 thicker than any of the succulent plants now known, is evinced in 

 numerous specimens. So different, indeed, do these plants appear 

 to have been from any vegetable now known, as to give full reason 

 for supposing them to have belonged to a tribe entirely lost. 



Every oryctologist is aware of the difficulty of giving names to 

 fossil plants, each schistous stratum being an immense herbarium, 

 of which every separated schist is a folio, on which are depicted 

 the figures of plants of the old world : most of which it is proba- 

 ble no longer exist. Not only is it difficult, with many fossil 

 plants, to determine the species and genera in which they should 

 be placed ; but frequently it happens, that their appearances differ 

 so much from those plants with which we are acquainted, that it is 

 not possible even to determine their proper station in the natural 

 orders of plants. Among the remains of plants of this latter de- 

 scription may be mentioned those of which we have been just 

 speaking, the appearances of which seem to be such as to defy 

 description. You have already observed the avowed inability of 

 Dr. Woodward and Mr. Da Costa to form a judgment of their na- 

 ture, or give a satisfactory account of the appearances which they 

 present: a later writer, M. Walch, appears to have experienced no 

 less difficulty. In one specimen of this kind, he remarks, the ap- 

 pearances are such, as would have been produced by the feet of a 

 kid, and even suggests that the impressions on its surface might 

 have been the track of some such animal. 



To particularize all the different known plants which have been 

 supposed, by different authors, to have been seen in a fossil state, 

 would employ much more room than can be allotted here for that 

 purpose, especially when we are, at the same time, taught how little 

 reliance can be placed on the opinions thus given. It is, perhaps, 

 sufficient to say, that the fossil plants of Germany, have been de- 



