474 



MESOZOIC TIME. 



tives of the Salmon and Perch families. The teeth of Cestraciont 

 Sharks are common. 



The class of Reptiles, in the earlier part of the Cretaceous period, 

 included the Iguanodon and Teleosaur. Both then and later, there 

 were Plesiosaurs and Icthyosaurs ; other swimming Saurians, called 

 Polyptychodon by Owen, nearly fifty feet long ; over a dozen species 

 of Pterodactyls, one of which was twenty-five feet in the spread of its 

 wings ; also, in the later part, a Mosasaur, probably forty-five feet long 

 (Fig. 873) ; besides other large species. 



Fig. 873. 



Mosasaurus Hofmanni ( x Jg )• 



Of the class of Birds, two species have been found near Cambridge, 

 England, about as large as Pigeons, and probably related to the Gulls. 



Characteristic Species. 



1. Protozoans. — (a.) Sponges. — Tig. 860, Siphonia lobata, from the Chalk- 

 Over one hundred species related to the Sponges occur in the Cretaceous strata of Eng- 

 land. Scyphia, Spongia, and Ventriculites are the more common genera. 



(b.) Rhizopods. — Fig. 856, Lituola nautiloidea Lam.; Fig. 857, Flabellina rugosa 

 D'Orb.; Fig. 857 a, profile of same; Fig. 858, Chrysalidina gradata D'Orb. ; Fig. 859, 

 Cuneolina pavonia D'Orb.; Fig. 859 «, profile of same; all much magnified. Other genera 

 are Rotalia, Textularia, Nodosaria, etc. The Chalk formation of England has afforded 

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

 them two species of the genus Orbitolina, an American species of which is represented 

 in Fig. 829. 



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

 chosmilia, Parasmilia, Micrabacia, etc. 



(b.) Echinoderms. — Species of the genera Cidaris, Biadema, Cyphosoma, Heviiaster, 

 Cardiaster, Galerites, Holaster, Micraster, etc. ; also Crinoids, of the genus Marsupites,. 

 etc. 



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

 Flustra, Cricopora, etc. 



(b.) Braehiopods. — Numerous species of Terebratula, Terebratdla, Terebratulina T 

 Rkynchonella, Crania, Thecidea^ etc. 



