Plat. 



682 



Illust. Devon. Foss., 1876; Pal. N. Y. Vol. V, ii, 1879, page 17, 

 plate 7, figs. 1, 2, opposite sides of an internal cast, showing 

 cross lines of broad tubercules; former surface no doubt 

 strongly spiny, [like Conrad's P. dumosum. a fine figure of which 



Villa, ,, ^lumt)^^^V^^Co7i^f 





I add here from Hall, Pal. N. Y. Vol. V, ii, plate 6, fig. 1, al- 

 though not yet reported found in Pennsylvania, to show how 

 the spines were set into these shells.] — In Pennsylvania, re- 

 cognized by C. E. Hall, in Spec. 807-12, of Fellows' and 

 Genth's Collections, 1875, at G. Kintner's farm. 1 mile south- 

 west from Marshall's Falls, Monroe county. — Upper Helder- 

 herg limestone. VIII a, 



P. undulatum, Walcott, 1885. VIII, 



P. undulostriatum, Hall, 1859. VI 



P. unguiforme, Hall, 1859. VI, 



P. uniseriale, Nicholson, 1874. VIII a, 



P. unisulcatum, Hall, Pal. N. Y., Vol. 3, 1859, page 316. 



