: 
; 
J. J. Stevenson— Upper Devonian Rocks of Pennsylvania. 429 
for they are found in great abundance throughout the section 
and they are as well preserved as Chemung fossils usually are 
in New York. With these are immense quantities of fucoids, 
such as are characteristic of the Portage or lower Chemung in 
New York. But in the whole section there is not an Anodonta, 
not a fish-plate, not any fossil of any sort which can in any way 
be identified as belonging to the red Catskill of New York. 
It is more than probable that the section represents only the 
lower portion of the Chemung and that not only the red Cats- 
kill, but also the upper portion of the Chemung is wanting in 
this part of Pennsylvania.* 
What then has become of the great Catskill group? € 
upper or gray Catskill is represented, no doubt, by the Pocono 
or Vespertine sandstone, but the lower or red Catskill has dis- 
<a s Nor is this disappearance at all strange. It is sim- 
ply what might have been expected. 
Professor H. D. Rogers, on pp. 141 and 142 of vol. i, of his 
Final Report, shows with what rapidity the Ponent or red 
Catskill thins out toward the northwest; that it is 5,000 to 
6,000 feet thick in the southeast belt; 2,500 to 1,000 feet in 
the northwest belt; and 400 to 0 feet in the fifth belt; the 
diminution in each belt being distinct as one goes nor’ 
or even west. No details are given respecting the variations of 
the group in a due west direction or towards the southwest, 
most probably because no possibility of tracing the group ex- 
isted then any more than now. The presence of Ponent rocks 
is incidentally mentioned in notes upon the southern Allegha- 
nies and the gaps through Chestnut and Laurel Ridges, but these 
observations were evidently regarded as too detached and too 
unimportant to be of value, since no reference 1s made to them 
in the general summary of the group given in vol. 1 of the 
Final Report. : ath: : 
All the evidence points in one direction. Itis impossible by 
any stratigraphical work to make direct connection between the 
localities under consideration and those where the age of the 
rocks is settled beyond dispute; the lithological characters of 
* In the Proceedi erican Philosophical Society, vol. xvii, p. 270, it is 
stated that at 200 feet below the Pittsburg bal y in the Lower Bar- 
e . 
No explanation is necessary further than to say that the species were wrongly 
identified. I haye examined the specimens and have recognized the following: 
Species :— 
Lophophyllum proliferum M’C., Athyris subtilita H., Spirifer planoconvecus Shum., 
Orihis carbonaria Swal., Chonetes granuifera Owen, Productus pertenuis Meek ?, 
Hemi } M. and H., Lima retifera Shum., Astartella vera 
These are usually thought to be quite characteristic of the Coal measures. 
Am. Joon. Sc1.—TuHirp _— Vou. XV, No. 90.—Jung, 1878. 
