1 82 CRETACEOUS PALEONTOLOGY. 



necessarily be found to conform with their history in New Jersey, 

 The alternation of the two^ faunal facies may or may not occur. 

 In certain regions it may be found that the one or the other 

 facies persists through the period, or if the alternation does occur^ 

 the recurrences may be less or more frequent than has been. 

 observed in New Jersey. In tracing their relationships with other 

 Cretaceous faunas in North America, it is found that they have a 

 close analog in the faunas of the Montana group of the West and 

 Northwest. Just as in the New Jersey area an alternation of 

 shallower and deeper-water faunas is a conspicuous feature, sa 

 in the Northwest a shallower-water fauna described first as the 

 "Pox Hills" fauna and supposed to be characteristic of the upper 

 division of the Montana, has been found tO' be recurrent at various- 

 horizons throughout the entire Montana series. In regard to> 

 this fauna Stanton says "Faunas similar to that of the Fox Hills- 

 sandstone have a great vertical range and are likely tO' be found 

 at any horizon within the Montana group where a littoral or 

 shallow-water facies is developed."^ 



A comparison of the shallower-water facies of the Ripleyian 

 fauna in New Jersey with this Fox Hills fauna of the Northwest 

 shows many characteristics in common. The following Fox 

 Hills species have been identified in these New Jersey faunas : 

 Micrdbacia americana^ Cuspid^ria ventricosa, Cyinella undata, 

 Pteria petrosa. Many others of the New Jersey species are 

 clearly allied very closely to Fox Hills forms, and further critical 

 studies with the comparison of large collections from the two 

 areas will doubtless lead to the recognition of many more species- 

 common tO' the two faunas. 



The deeper-water Cucidlaed fauna of the New Jersey area does 

 not so clearly correspond with the deeper-water Pierre fauna of 

 the northwestern Montana group, this fauna in New Jersey, as 

 well as the shallower-water facies, having much, in common with 

 the Fox Hills fauna of that region. However, certain genera 

 such as Inoceramus and the oyster-like forms are more character- 

 istic of the deeper-water facies in both regions. 



In connection with the present investigation of the New Jersey 

 faunas it has not been practicable to make as extensive nor as 



' Bull. U. S. G. S., No. 2S7, p. 66. 



