Devonian Era in the Ohio Basin. — Claypole. 241 
1. The Invertebrate Fauna of Eastern Appalachia. 
The scanty lists of fossils given in the report of the first 
geological survey of Pennsylvania, and others that have inci- 
dentally appeared in those of the second survey and elsewhere, 
fail to do justice to the abounding life of some of the De- 
vonian beds, which are literally crowded with organic remains. 
Alternating with these again are beds almost completely barren. 
The following tables, drawn up from the writer's own 
material, nearly every specimen mentioned having been collected 
by himself, well illustrate both the above statements. Several 
counties are represented on these lists, from Monroe in the 
northeast to Huntingdon in the centre, so that no inconsider- 
able area of the eastern part of Appalachia is covered by the re- 
sults. 
In the examinations of these tables several facts should 
be borne in mind. In the first place, the Corniferous limestone 
is lacking over the whole region involved, except in Monroe 
county, so that the absence of entries on that line has no bear- 
ing on the question. Secondly, the separation of the Hamilton 
into three parts, by the intervention of the sandstone, affords 
ground for a division of its fossils into the same number of 
horizons. Of these, the lower shale is remarkable for an al- 
most barrenness of fossils, diligent and continued search having 
been rewarded by only two or three imperfect specimens. The 
overlying sandstone is in certain places rich in some forms, one 
of these a Rensselacria (Neivberria) — being absolutely limited 
to this horizon. But the upper shale is one of the most pro- 
fusely crowded beds wherever it occurs in the region, being 
comparable only in this respect with the limestone shales of the 
Silurian below it. This marked difference is not easy of ex- 
planation, as the two strata are closely similar in aspect, color, 
texture and composition. Each of them is about 300 feet in 
thickness. 
The overlying Genesee and Portage shales are again nearly 
barren but hold their peculiar New York species, with a few 
others surviving from the Hamilton and even from the Marcel- 
lus below them, — the black shale fauna being persistent and re- 
curring with congenial conditions. 
In the sandy shales of the Chemung, a profusion of organic 
remains is found, many of which ascend to high levels, even 
