328 BOTANICAL GAZETTE [NOVEMBER 
KNOWLTON,? in a survey of all the described species of Cordaties 
and Dadoxylon, describes twenty-four species as showing growth 
rings either distinctly or indistinctly. Of these, Cordaites ouangon- 
dianum Dawson from the Middle Devonian of New Brunswick and 
Dadoxylon (Cordaites) annulatum Dawson of the Middle Carbonif- 
erous of Nova Scotia must be excluded because the original 
descriptions were based on a complete misinterpretation of struc- 
tural features (PENHALLOW, p. 56). Of the other species, nine are 
from the Carboniferous, the remainder from the Permian. Of the 
Carboniferous species, seven are from latitudes south of England, 
and of these four species are from latitudes as far, or practically 
as far south as Prince Edward Island, as follows: Nova Scotia 
(46° N.), three species; Niederburbach in Upper Alsace (47°45’ N.), 
one species showing distinct rings of growth. Most of the Permian 
species range in latitudes from 50°15’ N. to 51° N., but one species, — 
with distinct growth rings, is recorded from Val d’ Ajol, Department 
of Upper Saone, France (47°40’ N.). 
These data show that the extreme southern extension of a 
variable annual temperature in the Triassic period is not particu- 
larly remarkable. As far back as the Middle Devonian (Genesee) — 
there must have been noticeable variations in climate in fairly 
low latitudes, in order to effect even the slight variations in wood 
formation noted, while in the Carboniferous the development of 
distinctly marked annual rings of growth indicates a pronounced 
seasonal variation in the climate of that period, even in far southern 
latitudes. This is also shown, but less markedly, in the Permian. 
The specimen from the Upper Carboniferous of Bartlesville, 
Oklahoma, represents part of a trunk of a tree of considerable size, 
for in the section of trunk preserved, a radius of 5.5 inches of wood 
is shown with neither pith on one side nor cortex on the other. 
PENHALLOW gave the name Cordaites recentium to an undescribed 
species from the Permian or Permo-Carboniferous of Prince Edward 
Island, which Sir Witt1AM Dawson had regarded as related, if not 
identical with C. materiariwm Dawson from the Upper Carbonit- 
erous of Nova Scotia, Newfoundland, Illinois, etc. The species 
was not figured, but after a comparison of PENHALLOW’s description 
4Proc. U.S. Nat. Museum. 12:601-617. 1890. 
