190 GEOLOGY. 



In the interior sea, the ammonoids, the nautiloids, Inoccramus, and the 

 oysters were conspicuous forms. The gastropod element was prominent in 

 the Fox Hill stage, and the foraminifers in the chalk deposits. In the Colorado 

 series, Inoceramus and several genera of ammonites constitute the most con- 

 spicuous element in the fauna, associated however with many forms of pelecy- 

 pods and gastropods. In the Montana series the faunas much more closely 

 resemble those of the Atlantic border province, a considerable number of 

 identical or closely allied species being common to these faunas and those of 

 New Jersey. 



In the Pacific-coast province, the (Upper) Cretaceous faunas are less exten- 

 sive than those of Comanchean age, but the Cretaceous faunas, like the Coman- 

 chean, are quite distinct from the contemporaneous faunas which lived in the 

 more easterly provinces. They include several ammonites of types quite differ- 

 ent from those of the interior and the east, besides various genera and species 

 of pelecypods and gastropods. 



Note. — From a paper which came to hand after this chapter was in type, it 

 appears that certain beds of Colorado, New Mexico, and Oklahoma, which have 

 usually been regarded as a part of the Dakota formation, are really Comanchean, 

 and of marine origin. 1 



1 Stanton Jour, of Geol., Vol. XIII. 



