XLII INTRODUCTORY REMARKS. 



so far as those of the Upper Missouri correspond to those of New Jersey, will 

 be readily understood. For instance, the lowest bed (marked J ) in the New 

 Jersey section almost certainly represents the Dakota group (No. 1) of the 

 Upper Missouri section ; at least, it holds the same position at the bottom 

 of ihe series, and, like the Dakota, group, it contains numerous leaves of the 

 higher types of dicotyledonous trees. These leaves from New Jersey have 

 not, it is true, been thoroughly compared with those found in the Dakota 

 group, but the general aspect of the specimens from these two distantly- 

 separated localities is the same, and indicates a similar flora; and most of the 

 genera, as well as some of the species, are believed to be identical.* 



As in Mississippi and Alabama, the Fort Benton and Niobrara groups 

 seem to have no representatives in New Jersey, nor, so far as yet known, 

 anywhere east of the Mississippi. That the beds marked c, d, and e, in the 

 New Jersey section, represent the division No. 4, called the Fort Pierre 

 group in the Upper Missouri, and that the New Jersey bed b is equivalent to 

 the Fox Hills group (No. 5) of the Upper Missouri section, we have, it is 

 believed, entirely satisfactory palseontological evidence. 



In an article by Professor Hall, on the distribution of the Cretaceous rocks 

 of America and their relations as developed at distantly-separated localities in 

 this country, published in the July number of the American Journal of Science 

 and Arts for 1857, it will be seen that he adopted essentially the same con- 

 clusions in regard to the parallelism of the subdivisions of the Cretaceous 

 series ot the Upper Missouri and New Jersey ; also in an article on the 

 same subject in the United States and Mexican Boundary Survey, published 

 in 1858.f 



* Since writing the foregoing, the author has observed that Professor Lesquereux states, in Dr. 

 Hayden's Report of 1874, p, 360, that lie had examined a collection of the leaves front this horizon in 

 New Jersey, belonging to Professor Cook, and adds that they "represent many species identical with 

 those of the Dakota group, or, at least, evidently related forms. Both Magnolia Capellini, and especially 

 AI. alternans, are among them"; thus confirming, in the most decided manner, when taken in connec- 

 tion with the other facts, the parallelism of the lowest Cretaceous bed in New Jersey with the Dakota 

 group of the Upper Missouri. 



Dr. Hayden and the writer once collected many of these New Jersey leaves from a locality on 

 Earitan River, with the view of comparing them with the collections from the; Dakota group ; but, before 

 this could be done, the specimens were all saturated with water during the lire at the Smithsonian Insti- 

 tution, and, for the most part, crumbled to pieces. 



tThis volume of the United States and Mexican Boundary Survey bears the date of 1857 on the 

 title-page, but it was not published until the summer of 185S. See Am. Jour. Sei. and Arts for July, 1859, 

 p. 149. 



