288 RECORD OF SCIENCE FOR 1887 AND 1888. 



tains a large number of strongly Jurassic types. The Wealden fur- 

 nished the largest number of identical species, the Cenomanian next, 

 and the Urgoniaij next. Of allied species, although the largest num- 

 ber occurs in the Oolite, the Cenomanian, Urgonian, and Wealden each 

 furnish many. Taking the identical species, and considering the Weal- 

 den as Cretaceous, the flora would appear to be decidedly Cretace- 

 ous, but if this showing is considered in the light the Jurassic types 

 cast upon it, it is difficult to believe it to be higher than Wealden or 

 Neocomian." But he says at the close that in case the stratigraphical 

 and animal remains should require such reference, "the plants do not 

 present any serious obstacle to reference of the Potomac formation to 

 the Jurassic." 



C. A. White (280) publishes a very interesting article on the inter- 

 relation of contemporaneous fossil faunas and floras, an addition to the 

 literature already contributed by him in this line. The present paper 

 considers the relationship between the invertebrate faunas and floras 

 and the vertebrate faunas preserved in the range of deposits from the 

 Laramie group to the Bridger, inclusive. He considers that sedimenta- 

 tion was continuous during the whole time, and that there was for the 

 whole time, and within the region where the Laramie and Bridger de- 

 posits were being made, an unbroken continuity of invertebrate and 

 plant life. "If these conditions actually existed we must necessarily 

 conclude that the Puerco and Wasatch mammalian ftiunas were both 

 suddenly and independently introduced into the region where they are 

 now found from some other region where they previously existed," and 

 he concludes that "the Wasatch fauna existed somewhere contempora- 

 neously with the Puerco mammalia from which it differs so much, and also 

 contemporaneously with the Laramie dinosaurs, from which it differs far 

 more widely." In the latter part of the paper the author presents rea- 

 sons for considering it necessary to study the history of continental and 

 fresh- water faunas and floras distinctly from the marine faunas, and 

 that until evidence is obtained positively identifying faunas of the two 

 types of deposits, they should be classified separately. 



The same author (289) in a note to the editors of the American Nat- 

 uralist announces that he has found that Mr. Cummins was entirely 

 correct in his reported discovery of Mesozoic and Paleozoic types of in- 

 vertebrates commingled in one and the same layer of tbe Permian. The 

 deposits in which this discovery was made are in Baylor, Archer, and 

 Wichita Counties, Texas. 



Three papers by J. W. Dawson (62, 63, 70), although not of a pale- 

 ontological nature, are of interest to paleontologists. The author com- 

 pares the Eozoic and Paleozoic deposits of eastern North America with 

 the European series of deposits, and also with those of the Arctic basin. 

 De finds the geological series up to tbe Trias-Juras, and after an inter- 

 val again in the Quaternary, to be closely related on the borders of the 

 Atlantic on both sides, and far northward into the Artie regions, and 



