414 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvi. 



and whose aid iind interest in my work liave greatly increased the A'alue 

 of the present paper. The work of the local collectors of Cumberland, 

 Messrs. Frank Hartley, George M. Perdew, and G. M. Roeder, has 

 also l)een of much benetit. These united efforts have resulted in 

 uneai'thing many new species and new faunula? in wdiich the Cystidea 

 form an important part. The best material in the collections has been 

 deposited in the United States National Museum, and will serve as 

 the basis for a monograph of the Ontaric and Lower Devonic fossils 

 of Maryland, now in preparation for the Geological Survey of that 

 State, under the direction of Dr. W. B. Clark. 



('intilN'vIand Bashi. — The Ontaric and Devonic deposits, from the 

 Juniata to the close of the Oriskany, were laid down in an Appalachian 

 trough, which Ulrich and Schuchert" have termed the Cumberland 

 Basin. This basin was liounded on the west by the Helderbergian 

 barrier, which existed possibly from Clinton, but certainly from 

 Niagaran time, and extended from the region of Cayuga Lake, New 

 York, southwestward to west of Altoona, Pennsylvania, through west- 

 ernmost Maryland, central West Virginia, into eastern Tennessee. To 

 the east of this barrier and about parallel with it was the Appalachian 

 Valley fold. - Between these lay the Cumberland Basin, which steadil}'' 

 subsided from early Ontaric time to the close of the Oriskanian. The 

 area of greatest subsidence was in central Pennsylvania (Lewistown), 

 since here occurs the greatest thickness for nearly all the formations. 

 To the north and south the formations pinch out, but during Helder- 

 bergian time a transgression sets in which tirst attains the MohaAvk 

 River in New York and subsequently spreads as far south as Hancock 

 County, Tennessee. During the Becraft of Helderl)ergian time, in the 

 western area of the Cumbei'land Basin, throughout West Virginia, 

 Maryland, and southern Pennsylvania, little deposition took place, l)ut 

 about 60 miles east conditions were normal and here occur faimas of 

 Becraft time. This sea spread north to the Mohawk River, but south 

 of Covington, Virginia, it had no great extent. In the western area 

 the Lower Oriskany black chert rests conformablj" upon, but sharpl}' 

 separated from, the late New Scotland shale zone. In the eastern area 

 nothing as yet has been foimd <'omparable with the Lower Oriskany 

 of the Cum})erland region, and it may be that no deposits of this time 

 were there laid down. During Upper Oriskany time sedimentation was 

 agaiji general and continued until the close of the Maryland Oriskanian. 

 Then a land condition prevailed in this basin south of middle Pennsyl- 

 vania, throughout Esopus and Onondaga time. To the north of middle 

 Pennsylvania, however, the Oriskanian sea continued, and linally, in 

 late Oriskanian time (Decewville), the Atlantic fauna spread l)y way 

 of the Mohawk depression into the Mississippian province. The 



« Report of the New York State Paleontologist, 1901 [1902], i)p. 647-652. 



