determining Fossil Plants. St2!7 



If the leaves are small, their absence may be due to incomplete 

 development ; but if the leaves are large and irregularly divid- 

 ed, we may have an indication of some kind of marine plant. 

 When leaves are small and are densely imbricated, they are 

 generally considered by fossil botanists to belong to either 

 Lycopodiaccae, or Coniferae ; and there is so little to distinguish 

 thbse families in a fossil state, that there is scarcely any means 

 of demonstrating to which such genera as Lycopodites, Lepido- 

 dendron, Juniperites, Taxitcs, and the like actually belong. 



It would be easy to extend these observations much further, 

 but to dwell at length upon this branch of the subject, would 

 carry us far beyond our present limits. We will, therefore, 

 bring our remarks to a conclusion, by calling attention to some 

 of those points, to the elucidation of which, it is most to be 

 wished, that geologists, who have opportunities of collecting fos- 

 sil plants, would apply themselves. 



In the first place, evidence is wanted as to plants to which 

 the cones called Lepidostrobi, the leaves called Lepidophylla, and 

 the fruit named Cardiocarpa, respectively appertain. Are they 

 all portions of species of the same genus, or, as seems more pro- 

 bable, is not Cardiocarpon a p^rt of a plant of a totally differ- 

 ent affinity ? Secondly, what were the leaves of Sigillaria and of 

 Stigma ria.? Of the latter, something is known ; but the leaves 

 are always so crushed, that no notion can be formed of their ex- 

 act nature. Mr Steinhauer says he has traced them to the length 

 of 20 feet ! In the third place, to determine the leaves of any of 

 the fossil stems that at present are only in the latter state, such as 

 Stembergia, Bucklandia, Cycadeoidca, Gaulopteris, Exogenites 

 and Endogenites, would be to supply a great desideratum. Again, 

 what was the real nature of the stem of Calamites.'' Was it an an- 

 nual shoot, proceeding from a perennial horizontal rhizoma, like 

 that of Juncus, &c. ? Had it any leaves, and if so, were they of 

 the nature of those figured in our-work, as probably belonging to 

 Calamnites nodosus, but considered by Sternberg and Brongniart 

 a distinct genus, which they call Volkmannia ? Another very 

 interesting object of inquiry is into the anatomical structure of 

 Lepidodendron, for the sake of settling whether that extensive 

 fossil genus belonged to Coniferae or to Lycopodiaceat, or to 

 neither. We know nothing of the leaves belonging to the fos- 



p2 



