466 STKATIGRAPHICAL GEOLOGY 



small Prototheria (Cimolomys and Selenacodori) related to the Jurassic 

 Plagiaulax, and some bones of true Marsupials referred to the 

 genera Didelphops, Cimolestes, and Telacodon. 



The following are some of the more important marine genera 

 which first appear in the Lower Cretaceous Series : 



Porifera. Barroisia, Catagma. 



Actinozoa. Brachycyathus, Holocystis. 



Echinoderma. Cardiaster, Catopygus, Discoidea, Toxaster ( Echino- 



spatagus), Enallaster, Goniopygus, Salenia. 

 Crustacea. Hoploparia, Meyeria, Mithracites. 



Brachiopoda. Kingena. 

 Lamellibranchia. Crassatellites, Pectunculus, Cyprimeria, Cyclorisma, 



Monopleura, Requienia, Toucasia, Sphferulites, 



Thetironia ( = Thetis). 

 Gastropoda. Aporrhais (Ornithopus, Dimorphosoma), Avellana, 



Eulima. 

 Cephalopoda. Desmoceras, Hoplites, Schlcenbachia, Crioceras, Aniso- 



ceras, Macro scaphites, Hamulina. 



The following are some of the more important genera which 

 make their appearance in Upper Cretaceous time : 



Porifera. Camerospongia, Cephalites, Chenendopora, Ccelopty- 



chium, Coscinopora, Doryderma, Guettardia, Halli- 

 rhoa, Leptophragma, Nematinion, Plinthosella, 

 Pharetrospongia, Plocoscyphia, Siphonia, Stauro- 

 nema, Ventriculites, Verruculina. 



Actinozoa. Caryophyllia, Ccelosmilia, Cyclocyathus, Micrabacia, 



Onchotrochus, Parasmilia. 



Echinoderma. Caratonms, Cottaldia, Galerites ( = Echinoconus), 

 Echinocorys ( = Ananchytes), Epiaster, Hemiaster, 

 Infulaster, Micraster, Bourgtieticrinus, Marsupites. 



Crustacea. Etyus, Eucorystes, Necrocarcinus, Palseocorystes, 



Paltega, Enoploclytia. 



Brachiopoda. Lyra ( = Terebrirostra), Trigonosemus. 



Lamellibranchia. Hippurites, Eadiolites. 



Gastropoda. Actseonella, Cassidaria, Columbellina, Cominella, Crepi- 



dula, Fusus, Pugnellus, Volutospina. 



Cephalopoda. Acanthoceras, Buchiceras, Baculites, Heteroceras, Mam- 

 mites, Pachydiscus, Placenticeras, Prionocyclus, 

 Prionotropis, Scaphites, Turrilites, Actinocamea, 

 Belemnitella. 



Pisces. Hoplopteryx, Corax, Macropoma, Osmeroides, Pletho- 



dus, Portheus, Ptychodus. 



Reptilia. Mosasaurus, Pteranodon, Ornithocheirus. 



I. LOWER CRETACEOUS SERIES 



As in the case of the Jurassic System it will simplify matters to 

 describe the rocks and fossils of the Lower Series in England and 

 Europe first, before dealing with those of the Upper Series. 



