Descriptions of Devoxian Fossils. 2-41 



The volutions are rounded on the back, and depressed on the sides, 

 and narrowed on the inner edge, giving a somewhat trianguhir form 

 to the transverse section. r' 



Tlie shell has been removed from the dorsal portion of the outer 

 volution, in the specimen described, so that the surface characters and 

 form of aperture cannot be fully ascertained. There is an appearance 

 of undulating concentric lines of growth, and indications ot a deep 

 notch in the center of the aperture, with a strong rounded lobe on each 

 side. 



Formation and locality. Upper Helderberg limestone ; five miles 

 west of Delaware, Ohio, on Sciota river. Collection of Rev.M. Herzer. 



-;^^ — Pal^oneilo parallela n. =^p. 



Shell of medium size, ventricose anteriorly, with a strong constric- 

 tion running obliquely from behind the beaks to the postero-basal angle. 

 Cardinal and basal margins parallel, the two valves when united being 

 of a somewhat cylindrical form, with length slightly exceeding twice 

 the height. Beak small, situated near the anterior end, and scarcely 

 rising above the hinge line. Anterior extremity rounded, posterior 

 end prolonged, and rounded above the postero-basal sulcus, but strongly 

 indented by it below the middle of the shell, giving a much shorter 

 basal line than the length of the shell above. Hinge-character, not 



ascertained. 



Surface marked by irregular concentric lines of growth, sometimes 

 forming strong, irregular varices. 



This species closelv resembles Palmneilo emarginata Conrad, of 

 the Hamilton group of Xew York ; but differs in being destitute of the 

 regular elevatecl and equi-distant varices of the surface so constantly 

 characterizing that species. 



Formation and locality. Waverly sandstone ; Newark and Bagdad, 

 Ohio. 



NOTICE OF TWO NEW SPECIES OF FOSSIL SHELLS FROM THE POTSDAM 

 SANDSTONE OF NEW YORK. 



The discovery of new forms of organic remains in the rocks of the 

 Potsdam period of New York is of such rare occurrence that it has 

 been thought proper to notice the two following species, obtained at 

 the chasm^near Keeseville, New York, during the summer of 1867, 

 from a layer near the base of the cliff, at the stairs used in descending 

 the chasm. The layer contains, besides the following species, numbers 

 of a small Trilobite {Gonoeephalites minutus Brad.) in fragments, and 

 is just above the bed which contains the Oholella _^rm«=Lingula 

 prima Conrad, and Lingulepis a;i%w«=Lingula antiqua Hall. 



Of the patelliform shell here described, only two specimens were 

 obtained; of the other, several impressions or cavities left by the 

 31 r, 



