Series Northern Appalachian. Bituminous. Pennsylvania-Ohio. Illinois. Pennsylvanic { { Coal Measures { { { (*) (_Salt Fork_). { { Monongahela or Upper { Break. { { Productive Coal Measures { { { { Conemaugh or Lower Barren Ames { { limestone near middle: { { (*) (_Pitcairn_) Coal No. 6. { { { { { Freeport { { Allegheny or Lower { (*) (Cannelton) Coal No. 2 (*). { { Coal Measures { Kittanning (*). (Morris?)(_Mazon Creek_). { { { (_Linton_). { { { Clarion. { { Pottsville { { { { Home wood. { { Mercer. { { Conoquenessing. { { Sharon. (*) marks the position of the Amphibian-producing horizons in these regions. (After Schuchert.) The fossils at the "upper beds" are localized into special strata. At one place in the upper part of the deposit, in a reddish shale, one finds that insects are more abundant than they are lower down. The Crustacea seem to come from apparently the same shale. At the lower end of the deposit certain definite species of _Pecopteris_ are localized. It is an interesting fact that one seldom finds a _Neuropteris_ at the "upper beds." The most abundant fossils are the various species of _Pecopteris_ and _Annularia_. When specimens of _Neuropteris_ are found they are usually discovered at the lower end of the exposures. In one place behind the "island" very blue nodules, hard and flinty and with sometimes well-preserved specimens of _Pecopteris_, are found quite definitely localized. These nodules are apt to assume an irregular shape. These localizations of the fossils are, of course, what we would expect from our knowledge of the recent fauna and flora. There is, to be sure, more or less intermingling of the species. The myriapods, so far as they have been found, are also localized. Mr. Carr found 3 within a space of a few feet, but again these are found widely scattered. The exposures at the "upper beds" are about a quarter of a mile long. They disappear under a heavy ledge of sandy limestone. At the "lower beds" (plate 1, fig. 6), those further down the creek, conditions are quite different from those just described, although of the same horizon: the banks of the creek are higher and almost perpendicular, so that the chances of collection from the shales are fewer. The bed of the creek, however, is wider and there are more nodules washed out. The most abundant fossil at this place is _Neuropteris_. The nodules at the upper end of the exposure are all, almost without exception, barren of fossils. The exposures here are of about the same extent as the "upper beds," though the species are not so varied. Judging from the collections made while there, Arthropoda are more abundant at the "lower beds."