CLASSIFICATION AND CORRELATION. 183 



critical comparisons of the fauna with those of the Montana 

 group as would be highly desirable, but enough has been seen to 

 show that the relationships are close, far closer than would be 

 suggested by a mere comparison of the species here considered as 

 identical, and future studies will surely show many more identical 

 species as well as many which are closely allied. These relation- 

 ships are so close, in fact, that the name Montanan might per- 

 haps be extended U> embrace the faunas and their including sedi- 

 ments. 



In Europe the Cretaceous fauna which seems to be most closely 

 allied to this Ripleyian fauna of New Jersey and the Gulf-border 

 region is that of the Cretaceous beds at Aachen. This fauna has 

 been elaborately described and illustrated by Holzapfel 1 , and 

 when the opportunity is given for a critical comparison of col- 

 lections from these Aachen beds with collections of our American 

 forms, a considerable number of species will doubtless be found 

 to be common to the faunas. The Aachen beds are of Se- 

 nonian age, and in their upper portion are characterized by 

 Belemnitella mucronata, a close analog, as has been pointed out, 

 of the New Jersey B. americana. Furthermore, this Belemnitella 

 zone is highly characteristic of the higher Senonian beds of 

 England, France and Germany, and the occurrence of the zone 

 on opposite sides of the Atlantic is without doubt essentially con- 

 temporaneous, although in Europe it probably represents a longer 

 time interval than in America. 



In "An approximate correlation of the Atlantic coast Creta- 

 ceous formations" suggested by Clark, 2 his Matawan and Mon- 

 mouth divisions are referred to the Senonian, the Cliffwood beds 

 being considered as Cenomanian and the Raritan proper as 

 Albian, these latter correlations being based primarily upon floral 

 evidence. From the evidence of the invertebrate fossils, however, 

 as shown in the earlier pages of this report, the Cliffwood clays 

 cannot be removed from association with the super jacent beds. 

 As to the Raritan the invertebrate evidence is too meagre to be of 



1 Die Mollusken der Aachener Kreide, von E. Holzapfel, Palaeontographica, 

 vol. 34, pp. 29-180, plates 4-20; vol. 35, pp. 139-268, plates 8-29. 

 * Am. Jour. Sci., (4), vol. 18, p. 440. 



