362 The American Geologist. June, i89i 
in the Upper Devonian of Scaumenac bay, Lower Quebec. 
It is thought by- Dr. Dawson that three species of Psllophyton 
have been found at Perry,* P. gldbrum Dn. , which probably 
occurs in the Upper Silurian at Gaspe, is known in the Lower and 
Middle Devonian of Gaspe, Lower Quebec, and the Middle Devon- 
ian of N. B. ; P. elegans Dn. Middle Devonian of Gaspe and N. 
B. ; and P. prince_ps Dn. , whose range is given above. It will 
be noticed that this flora is more closely connected with the pre- 
Carboniferous than with the Caboniferous floras of Canada and 
New Brunswick, while in the United States it is related about as 
closely with the Lower Carboniferous as with the Chemung and 
Hamilton. 
A recent letter from Sir William Dawson, in which his views as 
to the age of the Catskill flora are expressed in a very concise 
manner, will form an appropriate termination to this review of 
that flora. The suggestion that the Devonian flora in migrating 
south and west possibl} 7 appeared at a higher horizon, a principle 
that has been frequently observed in the stud}' of marine faunas, 
would seem to offer an explanation of the somewhat different 
opinions as to the age of this flora, that are held by the several 
paleobotanists who have studied it in different geographical areas. 
The above sentence calls attention to the fallacy of attempting 
precise correlation for the geological formations of widel} T separa- 
ted regions from simply lists of fossils common to the formations, 
without careful study and consideration of the stratigraphy and 
other related geological facts. This rule was probably somewhat 
overstated by Huxle}', in his noted address before the Geological 
Society of London ;f but, a concise and modern exposition of this 
and other principles for the guidance of ' ' geologists concerning 
the correlation of formations and the interrelation of presumably 
contemporaneous fossil faunas and floras " was admirably enun- 
ciated by Dr. Charles A. White in 1889. § 
Dr. Dawson's letter is given below and since its distinguished 
author has studied this flora far more carefully than any other 
*Quart. Jour. Geol. Soc. London. Vol. XIX, 1863, p. 462. 
f Anniversary Address. Quart. Jour. Geol. Soe. London, Vol. XVIII, 
1862, pp. XL -1. In particular see p. XLVI where it is stated that "For 
anything that geology or. palaeontology are able to show to the contrary, 
a Devonian fauna and Mora in the British Islands may have been con- 
temporaneous with Silurian life in North America, and with a Carboni- 
ferous fauna and flora in Africa. *' 
gAddress by professor Charles A. White, vice-president, Section E, 
in Proc. Am. As. Adv. Science, Vol. XXXVIII, pp. 222-226. 
