EXPLANATION OF PLATES. 299 



FIG. 



175. Dianchora striata, (from Sow. Min. Con.) 



176. Plagiostoma spinosum, (from Sow. Min. Con.) 

 177- Spondylus Americanus, hinge. (See Frontispiece.) 



178. Plicatula gibbosa. Harpax, Parkinson. 



179. Pedum Spondyloideum, (from Sow. Gen.) 



Fam. Ostracea. 



180. Ostrea edulis. 



181. Folium. Dendostrea, Sw. 



182. Gryphaea incurva. 



183. Exogyra conica, (from Sow. Min. Con.) 



184. Placuna placenta. Gen. Placenta, Schum. 



185. Vulsella lingulata. 



186. Anomia Epliippium. 



187. Hinge of the same, with bony process. 



188. Hinge, showing the fissure. 



189. Placunanomia Cumingii. 



190. Hinge of the same, showing the fissure. 



191. Hinge of the unattached valve. 



192. Mulleria. (from Sow. Gen.) 



Fam. Rudistis. 



193. Spheerulites foliacea. (Radiolites is more conical.) 



194. Calceola Sandalina. 



196. Birostrites inaequiloba, internal cast of Sphserulites. 



197. a. Crania personata, dorsal valve ; b. C. antiquata, interior. 



(This would be more properly placed in Brachiopoda.) 



195. Hippurites Cornucopia, (from Blainville.) 



199. Hipponyx Cornucopia, attached valve. 



200. Upper valve of the same. 



Fam. Brachipoda. 



201. Orbicula lsevis. 



202. Terebratula Psittacea ; a. anterior margin, 



203. Atrypa reticularis. Trigonotreta, Konig. 



204. Cyrtia exporrecta. 



