478 



MESOZOIC ERA— AGE OF REPTILES. 



in deep seas. These are all extremely minute, but some of larger size 

 are found in the Cretaceous limestone of Texas. Those from the chalk 

 have already been given (p. 471). 



Sponges are extremely common in_the_-chalk, as they are also in 

 deep-sea bottoms of the present day. About one hundred have been 

 found in the chalk. 



Echinoderms. — The free Echinoderms are now for the first time in 

 excess of the stemmed. The Echinoids are especially abundant and 



Fig. 779. 



Figs. 778-780.— Echinoids of the Cretaceous op Europe: 778. Galerites albogalerus. 

 coidea cylindrica. 780. Goniopygus major. 



Dis- 



decidedly modern in type ; and in the chalk some genera are identical 

 with, and some species very similar to, those recently got from deep- 

 sea ooze. The above are from the European Cretaceous. 



Figs. 781, 



Fig. 781. 

 r82.— Lamellibranchs : 



Fig. 782. 



r81. Ostrea Idriaensis (after Gabb). 782. Inoceramus dimidius 

 (after Meek). 



Mollusks. — For the first time Lamellibranchs are fairly in excess of 

 Brachiopods. Among the latter the modern family of Terelratulm are 

 especially conspicuous. Among the former the most noteworthy fact 

 is the abundance of the Oyster family — Ostrea, Gryphcea, Exogyra, 

 etc. ; and the Avicula family, Avicula, Inoceramus, etc., some of which 

 are of great size. 



