Plat. 



680 



Platyceras symmetricum, Hall, 15th Regent's Report N. 



Ha 



Pal, A! K Vot^ 1/ \* ' />/ ;t , "^c^^^s^MM ^^^ IS^79^ 



Y., 1862; Pal, N. Y. Vol. V, ii, 1879, page 9, plate 3, selected 

 figs. 18, 19, 20,21, four views of a typical specimen showing 

 the general features of the species, fig. 20, showing the 

 symmetrically coiled back ; fig, 21, is accidentally com- 

 pressed on one side ; from Oanadaigua lake, N. Y. Hamilton 

 rocks^ VIII G. — In Pennsylvania, Perry county, Claypole's 

 (000, 1889) specimen 5-85, from W. Barnefct's mill outcrop 

 of Hamilton shale, VIII c. 



Platyceras tortum, Meek, Proc. Acad. Nat. Sciences, Phila. 



^'' 1871, Coalmea 



sur e s . — Pal. 

 Ohio, Vol. 2, 

 1875, page 345, 

 plate 20, fig. 10 

 a S, G. dorsal 

 and ventral 

 views of one, 

 p^l O^^^^^' "^^^^y^ and dorsal view 



of another 



specimen, retaining their thin shells, true Plat]/Geras^ and 

 therefore not, like the casts in Illinois, to be suspected of being 

 distorted MaGhrocheilus. — In Pennsylvania, seen by I. 0. 

 White in the highly fossiliferous Ferriferous limestone of the 

 Allegheny Goal measures,, at Shinn's quarry, Wampum, Lvaw- 

 rence county, Q2, 47, 106; and in Mercer county, Q3, p. 25- 

 also in Beaver, Butler and Armstrong, Q, 62 ; V, 146. — XIII ^ 

 From Stark Co., O. Goal measures, XIII 



Platyceras tortuosum. Hall, Pal. N. Y. Vol. 3, 1859, page 

 472, plate 113, fig. 1, 2, 4, difficult individuals of diff'erent sizes 

 (3, 5, omitted,) all casts; surfaces unknown ; very near to P, 



