124 



MANUAX OF THE MOILTJSCA. 



III. EANGE OF GENEEA IN TIME. 



1 



Genera, arranged in tlieir 

 Order of Appearance. 



Cambrian. 



Silurian. 



Devonian. 



Carbonif. 



Permian. 



Trias. 

 L. Jura. 

 U. Jura. 

 L. Cret. 

 U. Cret. 



Eocene. 



Miocene. 



Pliocene. 



Lituites, Eaphistoma, Obelus 









— 



Camaroceras, Atrypa, Pterinea 



Gomphoceras, Beilerophon, Pentamerus 

 Orthis, Conularia, Murcliisonia 



Spirifera, Athyris, Posidonomya 



Isoarca 









Conocardium, Megalodon, ciionetes '. 



Cardiomorplia 



Ortkoceras, Loxonema, Cyrtia 



Pleurotomaria, Porcellia 



Productus, Macrochilus, Streptorhynclius 



Goniatites, Pleurophorus 



Edmondia, Myalina 







— 



Acteonina 



Terebratula, Pinna, Cyprina ..' . 



Lima 





.^^ 







Gei-villia, Myoconcha 



Ammo7ufes, Naticella, Opis 



Trigonia, Isocardia, Thecidium 



Cerithium, Plicatula, Cardita 



Trochotoma, Tancredia, Giyphaea 













Ancyloceras, Inoceramus, Unicardium . . . 



A starte, Pholadomya, Corbis 



Nerinsea, Goniomj'a, Exogja-a 











Terebratella, Limopsis, Neaera, Argiope ... 



Baculitea, Cinulia, Eadiolites 



Physa, Paludina, Unio, Cyi-ena ... 



Aporrliais, Tornatella, Pyrula 



Pectunculus, Thetis, Crassatella 



Crenella, Chama 



Voluta, Conus, Mitra, Haliotis, &.c 



Helix, Auricula , Cyclostoma 



Pseudoliva, Eostellaria, Seraphs 



Purpura, Strombus 



Argonauta, Tridacna 









The genera of tlie older rocks are believed to be nearly all 

 extinct ; for altbougb tbe names of many recent forms appear 

 in the catalogues of Palaeozoic fossils, it must be understood 

 that they are only employed in default of more exact infor- 

 mation. Buccinum, Melania, and Mya have been long since 

 expunged ; and Modiola, Nucula, and Natica, are only retained 

 until the characters which distinguish them are better under- 

 stood. 



