PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 69 
abundant Opikina and Strophomena like S. medialis Butts. Besides having a 
fauna like that of the Wardell formation, the Hostler member is lithologically 
reminiscent of the Ridley, equivalent of the Wardell in the Central Basin of 
Tennessee. 
Housum member of Mercersburg formation.—This name was proposed 
by Craig (1949, p. 732) for the basal member of the Mercersburg formation 
exposed only in the eastern belts of central Pennsylvania. The type section is 
in the railroad cut 24} miles southwest of Marion. The member consists of 67 
feet of tan to medium-gray, fine-grained, argillaceous, slabby, cream- to bufi- 
weathering limestone with an interval of dark-gray, thin, crinkly, gray-weather- 
ing limestone near the top. The member thins to the northeast. It contains few 
fossils, but the presence of Leptaena (?) sp. cf. L. charlottae Winchell and 
Schuchert was regarded as so important that the member was transferred from 
the Shippensburg, where it had originally been placed, to the Mercersburg. As 
shown elsewhere in this monograph, this fossil is a long-ranging one and does 
not have the significance for correlation given it by some stratigraphers. The 
few brachiopods recorded from this member are: 
*Leptaena sp. cf. L. charlottae Winchell and Schuchert 
Lingula sp. 
Lingulasma sp. 
Opikina aff. O. ruedemanni Salmon 
*Sowerbyella ci. S. punctostriata (Mather) 
Hurricane Bridge formation.—This name was proposed by Miller and 
Brosge (1950) for 288 to 368 feet of calcilutite with occasional thin beds of 
buff shaly mudstone. Tetradium cellulosum is abundant in the lower 150 feet. 
The name is taken from exposures along and near the road southeast of Hur- 
ricane Bridge, Hubbard Springs (T.V.A. 170-NW) Quadrange, Va. Brachio- 
pods are uncommon. 
Ancistrorhyncha sp. 
Strophomena sp. 
Zygospira ? sp. 
Correlation of Hurricane Bridge formation—This formation underlies the 
Woodway formation of Miller which contains fossils of the Wardell and Witten 
formations and overlies the Martin Creek limestone, a probable Ward Cove 
equivalent. The Hurricane Bridge formation is thus in the position of the Ben- 
bolt formation and part of the Wardell but has the calcilutite facies with abun- 
dance of Tetradium. 
Jacksonburg formation.—This formation in northwestern New Jersey and 
adjacent Pennsylvania occurs in two physiographic provinces: The Appa- 
lachian Valley, and an extension of the New England Upland. In the Appa- 
lachian Valley the formation consists of 135 feet of high-grade limestone resting 
unconformably on the Kittatinny limestone. At the type section the lower 58 
feet are faunally different from the upper 77 feet, and the lower Division is sepa- 
rated from the upper by a conglomerate and a faunal change. The lower part 
