270 The American Naturalist. [March, 
GEOLOGY AND PALEONTOLOGY. 
Relations of Devonian and Carboniferous Faunæ.— Prof. H. 
S. Williams calls attention to the recurrence of Devonian fossils in 
strata of Carboniferous age in northwestern Arkansas. The fossils 
occur in a limestone formatida; about the equivalent of the Warsaw 
or St. Louis formations of Missouri, and referred to the lower third of 
the Carboniferous. Among the undoubted carboniferous forms occur 
numerousspecimens of Liorhynchus quadricostatum Vanuxem and Pro- 
ductella lachrymosa var. stigmata, onusta, etc., Hall. The entire fauna 
is closely allied to that of the Eureka District, Nevada, and of Shasta 
County, California, and the author accounts for the appearance of 
these Devonian species in the Arkansas Carboniferous rocks as a case 
of migration from the region where they had been living unchanged. 
This migration was brought about by an elevation of the western area 
sufficient to cause a diversion of ocean currents and the shifting of such 
species as endured the transport into the Mississippi Valley. 
In conclusion, Prof. Williams points out that during late Devonian 
and early Carboniferous time in the Appalachian province, diversity 
and alteration of deposits is marked by numerous successive and dis- 
tinct faunas, in the western continental province uniformity of prevail- 
ing calcareous sedimentation for long periods is marked by an abnor- 
mally long continuance of many of the Devonian species, while the 
central continental province, midway between the two, is marked by 
the recurrence of Devonian species far up in the midst of Carbonifer- 
ous sediments. This series of observations is confirmatory of the hy- 
pothesis that persistence of species without modification is associated 
with continuance of uniformity of conditions of environment, and that 
change in the successive faunas of geological time is associated with 
the change and rearrangement of the conditions of environment to 
which the fauna is subjected. (Am. Journ. Sci., Feb., 1895.) 
Characters of Glossopteris.— A fortunate discovery of a speci- 
men of Glossopteris, a fossil plant associated with the coal-bearing 
rocks of the southern hemisphere, near Mudgee, N. S. W., shows the 
attachment of the fronds to the caudex, bringing to light the following 
fi . 
The leaves were successively developed along the whole course of 
the stalk and were deciduous. They were both petiolate and sessile. 
