377 



especially Palmacites Goldimms, denote Eoceue; that the magnificent 

 species ^ahal Gray ana is allied to, and perhaps an aucestor of, Sahal major ^ 

 which in Europe appears at the beginuing of the Miocene ; and that Fla- 

 Ijellaria communis is extremely similar to ^ahal adagavensis, which is found 

 in the Eocene Superior of the south of France, but which has not been 

 figured till now. From all this and other points of rajyproacliement which 

 the celebrated paleontologist of France makes in regard to the species 

 of the lower group of the Lignite flora, he concludes as follows : * 

 " In resuming, and notwithstanding that Ahietites, which I consider as 

 a Cretaceous type, your first group seems indeed to be legitimately 

 Eocene, by its Ferns, its Palms, its coriaceous and prototypical Poplars, 

 its Cinnamomnm, iiud its Viburnunijas related to the Sezaue flora, and by 

 one of its Palms to the Upper Eoceue of Angers. If one would suppose 

 this flora more recent than the Eocene, he would have to admit such a 

 dissemblance between Europe and America that every comparison by the 

 floras between the geological stages of both continents should appear an 

 impossibility." The assimilation of American species with a number of 

 Miocene species published in Europe is considered by Saporta as doubt- 

 ful and not quite conclusive ; and he remarks also that though his 

 opinion on the age of the Lower Lignitic group is given according to 

 present impression, the great geographical distance renders the affini- 

 ties between compared localities very difficult to fix with precision, 

 even in supposing them contemporaneous. 



These quotations must be excused by reason of the importance given 

 now to the question of the age of the Lignitic, which, contro versed in 

 various ways, demands light, and has to be considered in every possible 

 point of view. The problem is not yet solved. Requested, as I am, to 

 contribute a share in the discussiou, by closely adhering to paleontologi- 

 cal evidence, and exposing it as far as it is given by fossil plants, I had to 

 enter into details in order to show its weight. And no better opportu- 

 nity could be afforded for this purpose than a review of the group of 

 plants obtained from Point of Eocks by Dr. Hayd.en. 



After completing the examination of Dr. F. Y. Hayden's specimens, 

 and when the manuscript had been already delivered to the printer, a 

 friend of mine, Mr. William Cleburn, of Omaha, a zealous explorer and 

 student of our American vegetable paleontology, sent to me a large box 

 of specimens, obtained, most of them, from the same locality. Point of 

 Eocks, where Dr. Haydeu had discovered his own. These specimens 

 tend to confirm, by some identical species and by relation of types of a 

 few new ones, the evidence exposed already in regard to the age of this 

 locality. It is, therefore, advisable to enumerate and describe them as 

 an appendix to the above exposition. They are as follows : — 



1. LeMNA ? BULL AT A, Lsqx. 



The species is represented by a few well-preserved specimens, clearly 

 exhibiting the characters formerly described. All the fronds are mixed 

 with floating rootlets. 



2. Salyinia attenxjata, sj). nov. 



Leaves small, one centimeter or less in diameter, opposite, joined at the 

 narrowed, slightly-pedicelled base, round or broadly oval, indistinctly 

 reticulate by vertical and parallel rows of quadrate, large cells, marked 

 in the middle by black spots, formed of very small, close cells, or j) ores, 

 without any trace of a middle nerve. 



■■• 111 letter, October 19, 1875. 

 No. 0—10 



