74 Cincinnati Society of Natural History. 



261 Orthis centrilineata, Hall. L. centrum, centre; Uneatus, lined. 



262 Clj^tie, Hall. Mythological. 



263 costata, Hall. L. costatus, ribbed. 



264 testiulinaria, Dalman. L. testudo, a tortoise. 



265 testudinaria var. c^'clus, James. Gr. kuJclos, a circle. 

 0(36 var. jugosa, James. L. Jm^/o^^s, mountainous. 



267 var. multisecta. James. L. multus, mucli ; sectus, cut. 



268 emacerata, Hall. L. emaceratus, thiu. 



269 var. Meeki, S. A. Miller. 



270 dichotoma. Hall. Gr. dicha, asunder; temno, I cut. 



271 disparilis, Conrad. L. dispariUs, dissimilar. 



272 Ella, Hall. 



273 erratica. Hall. L. erro, I wander. 



274 fissicosta, Hall. L. fissits, split ; casta, a rib. 



275 insculpta, Hall. L. insculptus, engraven. 



276 Morrowensis, James. 



277 occidentalis. Hall. L. occidentalism western. 



278 orthambonites. Pander. Gr. orthos, straight; cimhon (L. 



umbo), umbone. 



279 pectinella, Hall. Jj. pecten, ii com]:). 



280 Jamesi, Hall. 



281 perveta, Conrad. L.^^erre^^M^, very old. 



282 plicatella, Hall. L. plico, I fold. 



283 retrorsa, Salter. L. retrorsus, turned back. 



284 sinuata, Hall. L. sinaatus, curved. 



285 subquadrata, Hall. L. sub, quadratus, square. 



286 triplicatella, Meek. L. tris, three; pZ^'co, I fold. 



287 (Z3'gospira?) sectastriata, Ulrich. L. sectus, cut ; stf'i,i, 



ridge. 



288 biforata, Schlotheim. L. biforus, having two openings. 



289 biforata, var. 13'ux, Von Buch. L. lyux, a l^'nx. 



290 var. laticostata, James. L. latirs^ broad; costa^ a rib. 



291 var. dentata, Pander. L. den tat us, toothed. 



292 var. acutilirata, Conrad. L. acutus^ sharp; lira, a ridge. 



293 var. crassa, James. L. cimssus, thick, 



294 var. cypha, James. Gr. kuphos, bent. 



295 var. acuminata, James. L. acuminatus, shaii?ened. 



NoTK. — The opinions of the ablest Palaeontologists were 

 received in making most of the varieties here noted. 

 O. jjrofundo-sulcata,X)wen; 0. injtaia, James; O. pro- 

 longata, James, and O. annieana, James, are con- 

 sidered sj-nonyms of species above named. 



