5SG Systematic Paleontology — Upper Devoxiax 



it has been recorded tliere after the introduction of S[iirifcr disjunctus 

 and the proper Cheiiiiing fauna. 



This species, which according to Williams is the most prominent 

 member of the Hamilton fauna, occurs in the Jennings at two horizons, 

 the Parkhead and the loAver conglomerate zone of the Chemung. It is 

 very profuse locally in the Parkhead, associated with many other recur- 

 rent Hamilton species. It is less profuse, though locally abundant, in 

 the upper horizon, where it is also associated with recurrent Hamilton 

 species. 



Occurrence. — Jexxixgs Formation, Chejiung Member. Two and 

 three-quarters miles southwest of Pound, West Virginia ; Mann, Pennsyl- 

 vania ; vicinity of Pawpaw and Magnolia, West Virginia : northeast of 

 Pratt; Town Creek, 2691. Parkhead Member. Rocky Pun; roadside, 

 1 mile north of Pocky Run; Williams Road, east of Cumberland, 1-iGG 

 abundant; Williams Road, on Polish Mountain, 1289 abundant, lo.j^, 

 l;?U common, 1422, 1032. 1660 abundant; National Road, on Polish 

 Momitain, 1196; 2 miles north of mouth of Town Creek, 1282, 1350, 

 1642, 1723 abundant, 1842 abundant, 1917 common; Town Creek, 1605, 

 1679, 1863 abundant; 2 miles west of Pawpaw, West Virginia, 1795 

 common; Little Orleans; Fifteenmile Ci'eek, 1 mile north of Little 

 Orleans, 1714 alnmdant, 1746 abundant, 1773; Sideling Hill Creek, 

 21/2 miles above mouth, abundant; Woodmont, 1385; Hancock, 1600; 

 Millstone, 1772; Berkeley Springs, West Virginia, 1769 abiuidant. 



Collection. — Marjdand Geological Survey. 



Superfamily SPIRIFERACEA 



Family ATRYPIDAE 



Genus ATRYPA Dalman 



Atrypa reticularis (Linne)' 



Plate LV, Figs. 6-11 



Description. — This well-known species, the most widely diffused and 

 longest lived of all known organisms, is represented in tlic ]\raryland 



^ For full Illustration and synonymy of the Chemung form of this species 

 see Hall, Pal. of N. Y., 1867, vol. iv, p. 316, pi. liii, figs. 3-19, and Hall and Clarke, 

 Idem., 1894, vol. viii, pt. ii, pi. Iv, figs. 1-17. 



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