Beport of the State Geologist. 245 



O. oblata, Hall, 1859. Lower Helderberg. 



O. oblata var. emarginata, Hall, 1859. Lower Helderberg. 



O. occasus. Hall, 1860. Kinderhook. 



O. occidentali8, Hall, 1847. Hudson River. 



0. orbicularis, Sowerby. This species was identified in New York 

 by d'Archiac and d'Verneuil in 1812. It lias not been recognized by 

 American authors. 



0. orthambonites, " Pander species." Identified by Billings as occur- 

 ring in the Quebec group at Point Levis. 



Pander did not describe an Orthis orthambonites, but did describe 

 several species of. Orthambonites. Murchison and De Verneuil have 

 figured an Orthis calligramma var. orthambonites with which Billings 

 identified his Canadian specimens. These figures of the Russian 

 species show fine radiating lines upon the plications which is not the 

 case with Canadian specimens. Von Buch has described Orthis 

 orthambonites with which Billings' figures should, be compared; if dis- 

 tinct, it will be necessary to give Billings' species another name. 



O. parva, De Verneuil species. Doubtfully identified by Billings in 

 1866 as occurring in the Anticosti group. 



O. pecosi, Marcou, 1858. Upper Carboniferous. 



O. pectinatus, D'Orbigny, 1812. Devonian of South America. 



0. pectinella [Conrad mss.], Emmons, 1812. Trenton. 



O. pectinella var. semiovalis. Hall, 1847. Trenton. 



0. peduncularis, Hall, 1859. Lower Helderberg. 



O. peloris. Hall, 1863. Schoharie grit. 



O. penelope, Hall, 1860. Hamilton. 



O. jDenniana, Derby, 1874. Carboniferous of South America. 



O. pennsylvanica, Simpson, 1889. Chemung. 



0. pepina, Hall, 1863 = Orthisiiia pej^ina. 



O. perelegans, Hall, 1857. Lower Helderberg. 



0. perversa, Hall, 1857 = Streptorhynchus perversum. 



O. perveta, Conrad, 1843.' Chazy to Trenton. 

 ? 0. pigra, Billings, 1859. Chazy. 

 . 0. pisum, Hall, 1852. Syn. for Nucleospira pisiformis, Hall. 



O. planoconvexa. Hall, 1859. Lower Helderberg and Oriskany. 

 ? O. platys, Billings, 1859. Chazy. 



0. plicata, Vanuxem, 1842. Syn. for Spirifera vanuxemi, Hall. 



O. plicifera, [Leptsena plicifera Hall, 1847J. Chazy. 



O. plicatella, Hall, 1847. Trenton to Hudson River. 



O. pogonipensis, Hall and Whitfield, 1877. Chazy. 



O. porcata, McCoy, 1846. Trenton and Mid. Silurian. 



O. porcia, Billings, 1859. Chazy. 



