CRETACEOUS PERIOD. 



485 



Crocodiles have been reported from the European Cretaceous beds. 

 No remains of Birds or Mammals have yet been discovered. 



Characteristic Species. 



1. Protozoans. — (a.) Sponges.— Fig. 777, Siphonia lobata, from the Chalk. 

 Figs. 776 a to 776 h represent the siliceous spicula of Sponges, showing some 

 of the various forms they present. Over 

 one hundred species related to Sponge occur 

 in the Cretaceous strata of England. Scyphia, 

 Spongia, and Ventriculites are the more 

 common genera among the twenty enume- 

 rated. 



(6.) Hhizopods. — Fig. 778, Lituola nautiloi- 

 dea. Fig. 779, Flabellina rugosa; fig. 779 a, 

 profile of same. Fig. 780, Chrysalidina gra- 

 data. Fig. 781, Cuneolina Pavonia ; fig. 781 a, 

 profile of same. All are much magnified, the 

 species heing very minute, not exceeding half 

 a line in length. Other genera are Botalia, 

 Textilaria, Nodosaria, etc. The Chalk formation of England has afforded over 

 one hundred and twenty species and between twenty and thirty genera, and 



Siphonia lobata. 



Figs. 778-781. 



Rhizopods.— Fig. 778, Lituola nautiloidea ; 779 a, Flabellina rugosa ; 780, Chrysalidina gra- 

 data ; 781, a, Cuneolina pavonia. 



among them two species of the genus Orbitolina, an American species of which 

 is represented in fig. 750. 



2. Radiates. — (a.) Polyp-Corals. — Species of Cyathina,Trochocyathus, Tro- 

 chosmilia, Parasmilia, Micrabacia (formerly Fungia), etc. 



(b.) Echinoderms. — Species of the genera Ananchytes, Cidaris, Diadema, Cy- 

 phosoma, Hemiaster, Cardiaster, Galerites, Holaster, 3Iicraster, etc. 



3. Mollusks. — (a.) Bryozoans. — Genera Eschara, Escharina, Vincidaria, 

 Flustra, Cricopora, etc. 



(b.) Brachiopods. — Numerous species of Terebratula, Terebratella, Terebra- 

 tulina, Rhynchonella, Crania, Thecidia, etc. 



(c.) Conchifers. — Species of Grypheea, Exogyr.a, Inoceramus, Gervillia, Trigo* 

 nia, — all extinct ; also of Cardium, Astarte, Cardita, Corbula, Isocardia, Lima, 



