4 CRETACEOUS PALEONTOLOGY. 



Geological Survey of New Jersey and the U. S. Geological Sur- 

 vey. In the preparation of these volumes Prof. Whitfield la- 

 bored under great disadvantages in the way of collections. He 

 was dependent entirely upon the collections already made, chiefly 

 those of the Philadelphia Academy of Science, the State Geo- 

 logical Survey, and the Museum of Rutgers College, no new 

 collections being made especially for his work. Whitfield's mon- 

 ographs, however, have been of inestimable value for the reason 

 that in them descriptions of all the species of earlier authors, 

 originally published in many scattered papers which were in- 

 accessible to the larger number of students, were assembled, and 

 with them many new forms described. The weakness of Whit- 

 field's work lies in the lack, in a large number of cases, of a record 

 of the true stratigraphic position of the species discussed, large 

 numbers of the forms recorded from the "lower marl" being in 

 reality from some one of the formations of the "clay marl" 

 series. The author of the monographs, however, was in no way 

 responsible for this lack, since the necessary stratigraphic data 

 were not furnished him with the collections upon which his work 

 was based. 



The present report on the invertebrate fossils of the New Jer- 

 sey Cretaceous formations consists of two parts. Part I is a 

 discussion of the stratigraphic paleontology of the region, being 

 based upon very extensive collections made in the field by the 

 writer during the field seasons of 1903 and 1904. Accurate data 

 have been secured with all these collections which in the aggre- 

 gate are much more extensive than all previous collections from 

 the region combined. A large portion of all the species pre- 

 viously described from the region have been detected, besides 

 many hitherto unrecognized ones. It is believed that this por- 

 tion of the report will not only be of value in the further study 

 of the stratigraphy and paleontology of the region, but also will 

 be useful in future correlation studies of the American Creta- 

 ceous, especially that of the Atlantic and Gulf border regions. 



Part II of the report is devoted to the Descriptive Paleon- 

 tology, and is in large part a revision of, Whitfield's work in the 

 light of the more extensive' collections available and of our more 



