FOSSIL PLANTS. 



INTRODUCTORY REMARKS. 



The generic classification of the species of fossil plants, enumerated and de- 

 scribed in this paper, is the same as that in the second volume of this Report. 

 Perhaps it would have been advisable to modify, by subdivision, a number of 

 our genera, especially for some species of ferns, of which we have recently 

 obtained fruiting specimens, which seem to indicate a relation to peculiar spe- 

 cies of the present time. But as this Report is a mere continuation of the first, 

 a change of classification would have rendered it more obscure to the student, 

 and would have required a long discussion on the value of some of these new 

 genera, without any advantage to science. For the fructifications of the fossil 

 ferns are scarcely, if ever seen, except obscurely, through the substance of the 

 leaflets under which they are attached, and even when the position of the sort 

 or groups of fructifications relatively to the veins and veinlets, or to the bor- 

 ders of the leaflets can be ascertained, their true form, and especially the mode 

 of attachment and of dehiscence of their indusium cannot be recognized. The 

 natural affinity of these fruiting fossil fragments is, therefore, always more or 

 less uncertain, and a mere change of name, without sufficient authority, tends to 

 obscure, rather than to enlighten the classification. I have, therefore, merely 

 appended some remarks to all the species, which, by their known organized 

 parts, may differ in some way from the characters of the genera to which they 

 are united. I have also, in this paper, omitted to repeat descriptions of genera 

 and of species already given in the second volume of the Report, but have 

 added to the names such remarks as have been suggested by the discovery of 

 more complete specimens. In botanical palaeontology, we have to deal merely 

 with fragments, and none of these separate fragments are sufficient, in them- 

 selves, to indicate the general character of the whole plant to which they be- 

 long. The discovery of each part of a fossil plant adds, therefore, to our ac- 

 quaintance with a species, and the record and description of any of the separ- 



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