REVISION OP THE GENUS ORTHIS. 21 



O. testudinaria and O. el egantula group. (Shell punctate.) 



O. perveta, Conrad Chazy — Trenton. 



O. suba?quata, " " 



O. gibbosa, Bill ' ; 



O. Minneapolis, Winchell " 



O. testudinaria, Dalman Trenton — Hudson River. 



O. " var. multisecta, Meek _ " 



O. " " emacerata, Hall__. " 



O. " " Meeki, Miller " 



O. ? clytie, Hall Trenton. 



O. elegantula, Dalman Niagara. 



O. planoconvexa, Hall Lower Helderberg. 



O. concinna, " " " 



O. perelegans, " " " 



O. subcarinata, " .-- " " 



O. lenticularis, Vanuxem Corniferous. 



O. cyclas, Hall Hamilton. 



0. hybrida and 0. Vanuxemi group [Rhipidomys, (Ehlert]. (Shell punctate.) 



O. hybrida, Sowerby Niagara. 



O. tubulostriata, Hall Lower Helderberg. 



O. oblata„ " " " 



O. musculosa " Oriskany. 



O. Cumberlandia, " " 



O. Livia, Bill Corniferous. 



O. Vanuxemi, Hall " & Hamilton. 



O. Missouriensis, Swallow Chouteau. 



O. Burlingtonensis. Hall Burlington. 



O. Swallovi, Hall 



O. Thiemei, White " 



O. Michelini, L'Eveille Knobstone. 



O. Pecosi, Marcou Upper Carboniferous. 



0. resupinata and 0. proplnqua group [Schizophoria], (Shell punctate). 



O. circulus, Hall Clinton. 



O. multistriata, " Lower Helderberg. 



O. propinqua, " Corniferous. 



O. Iowensis, " Hamilton. 



O. Tulliensis, Vanuxem Tully. 



O. resupinoides, Cox Upper Carboniferous. 



Bilobites (Dicoelosia). (Shell punctate). 



D. biloba, Linn. Niagara. 



D. varica, Conrad Lower Helderberg. 



