Geological position of the Catskill group. — Prosser. 359 
of Perry, Maine ; and, Dictyo-cordaites lacoi Dn. is known only 
from the Lower Catskill of Meshoppen, Penn'a. 
In the range and distribution of the species mentioned above 
some doubtful references have been omitted and most of the for- 
eign localities have been ignored, because they offer no particular 
assistance in the solution of this question. The above summary 
is to be regarded as simply a preliminary one, based on published 
accounts of this flora, which will be somewhat modified when all 
the collections of Catskill plants have been studied. Up to the 
present time the collections of Devonian fossil plants of the 
United States have been widely scattered ; no paleobotanist has 
had the opportunity of studying all the material, and in fact some 
of the important specimens have scarcely been examined. It yet 
remains for a paleobotanist to describe the Devonian flora of the 
United States as Lesquereux did the Carboniferous or as Dawson 
has the Paleozoic flora of Canada. Yet, it is believed that the 
genus Archa-opteris may be regarded as including the predominant 
fern life of this period, which appeared, like the Holoptychius 
fauna, in the preceding Chemung stage and has continued for a 
considerable length of time in the Lower Carboniferous. If we 
accepted Dr. Newberry's correlation of the Devonian and Lower 
Carboniferous and drew the dividing line at the base of the Che- 
mung stage,* then the genus Archceopteris might be regarded as 
characteristic of the Lower Carboniferous. But, as professor 
Williams shows in the above paper, this does not agree with an 
accurate interpretation of the typical Carboniferous section and 
the professor has given proof elsewhere! that the Chemung stage 
- should be included in the Upper Devonian. 
Professor Lesley has recently published an interesting note upon 
the Pocono flora, which would apparently strengthen the claim of 
classing the upper portion of the Devonian with the Lower Car- 
boniferous. The general nature of the evidence may be seen from 
the following excerpts: "As this goes to press (October 23, 
1890) I received an important letter from Mr. Lacoe, of Pittston, 
Pa., saying that he has cursorily examined the contents of some 
of the boxes forwarded by his collector of fossil plants at the 
*See Mon. V. S. Geol. Sun., Vol. XVI. The Paleozoic Pishes of N 
A., pp. 23, 77, 84. 
fBull. U. S. Geol. Surv.. No. 41. On the fossil faunas of the Upper 
Devonian — the Genesee section. New York. Chap. I: Am. .lour. Sci , 
3d ser., Vol. XXXV, p. 54. 
