354 The American Geologist. June, isol 
Upper Devonian and Lower Carboniferous of Australia and Car- 
boniferous ( Coal Measures ? ) of China ; so that the evidence af- 
forded by the most prominent genus of ferns would be as strongly 
in favor of classing the Catskill with the Lower Carboniferous as 
with the Chemung or Upper Devonian. 
A short analysis of the American Catskill flora may be of some 
interest in connection with this subject. The Catskill of New 
York and Pennsylvania contains, so far as reported, thirteen spe- 
cies, of which number seven belong to the genus Arch a opterts. 
A few species that were described as from the Catskill have been 
omitted from the list, owing to the fact that a more accurate 
knowledge of the geology of the region has shown them to belong 
to the Oneonta sandstone, or Chemung ; but, it is thought that 
all the species mentioned in the following list occur in the Catskill 
as now restricted and defined. The species are as follows : 
1. Arccehopteris jacksoni Dri.* 
*In 1869 Schimper referred with doubt Cyclopteris jacksoni Dn. to 
Paleeopteris halliana (65pp.) Sch., now Archceopteris (Traite pal. veg., 
Vol. I, p. 478.) Dawson in 1871 objected to this identification, stated 
that it was a distinct species and put it in what was then considered 
the sub-genus Archoeopteris of Cyclopteris ( Fos. Plants Dev. and Dp. 
Sil., Pt. I, p. 48.) Schimper in 1874 accepted Dawson's defence of the 
validity <if the species and gave it as Paleeopteris jacksoni (Dn.) Sch. 
( Traite pal. veg., Vol. III. p. 4s4. ) In 1882 Dawson elevated the sub-genus 
Archmopteris to generic rank and gave some additional information 
about A. jacksoni Dn. (Fos. Plants Erian and Dp. Sil., Pt. II, p. 100.) 
In 1888 it is mentioned as A. jacksoni and figured on p. 74 of Dawson's 
"Geological history of plants:" while its author in 1889 again stated 
that it is a distinct species from A. halliana (2d Geol. Surv. Penn'a, P 4 , 
Vol. I, errata p. VI.) 
The Cyclopteris jacksoni Dn. is stated by Dawson in 1862 
(Quart. Jour. Geol. Soc. London. Vol. XVIII, p. 319 ) to have 
been found at Montrose, New York, which is undoubtedly Pennsylvania. 
Professor Hall in 1S63 (16th An. Rep't. of the Regents of the State of 
X. Y. on the State Cabinet of Natural History. Appendix D., p. 110) 
identifies the specimen found near Montrose. Penn'a. and described by 
Vanuxem (Geol. X. Y., Pt. Ill, p. 192 and fig. 58 on p. 191) as Cyclop- 
teris jacksoni (?) Dn. Dawson in 1871 (Fos. Plants Dev. and Dp. Sil., 
Pt. I. p. 46) wrote that "A specimen, obscure in details, but which 
must belong to this [A. rogersi Dn.] or the previous species [A. halliana 
( Gopp.) Lx.], occurs in professor Hall's collection, from Montrose, Pa." 
On p. 45 Cyclopteris jacksoni Dn, is simply credited to the Dpper De- 
vonian of N. Y.. without giving the locality: but, on p. 91, fig. 109 of 
pi. xv it is said to be a pinna of Cyclopteris (Arcluvoptcris) jacksoni from 
Montrose, Penn'a. In the Acadian Geology, 3d ed., 1S7S, it is stated 
on p. ">47 that ••large specimens [of C. jacksoni Dn.] occur in the col- 
lection of professor Hall from the Old Red sandstone of Montrose, Xew 
York." It appears from this that it was not a single specimen that 
was identified as C. jacksoni, or C. rogersi; but, that both species were 
seen from collections made at Montrose. Penn'a. 
In explanation of this ambiguity Dr. Dawson wrote me as follows, 
