188C.] NEW YORK ACADEMY OF SCIENCES. 133 



An interesting banded muscovite from Bear Creek, El Paso 

 Co., Colorado, is composed of twenty alternate layers of brown 

 and white muscovite. The crystal measures 43 mm. in its great- 

 est diameter. 



A siiecimen of quartz, from Arizona, is covered with an altera- 

 tion of chalcedony and quartz after bent crystals of calcite. 

 The crystals replaced were 12 mm. long by 4 mm. thick ; and 

 the alteration is a replacement pseudomorph. 



Dr. J. S. Newberry read a paper upon 



THE CRETACEOUS FLORA OF NORTH AMERICA. 



(Illustrated by drawings and lantern views.) 

 (Abstract.) 



The first information in regard to the vegetation which cov- 

 ered this continent in the Cretaceous age was furnished by a col- 

 lection of fossil plants sent from Vancouver's Island by Mr. 

 George Gibbs, in 1858. These consisted of leaves of angiosperms 

 and palms described by the speaker in the Proceedings Boston 

 Nat. His. Soc, 18G3. With them were casts of Inocer'amiis and 

 Bacidites, which were indicative of Cretaceous date. 



Subsequently Mr. Meek, Dr. Hayden, and the speaker ob- 

 tained from the "Dakota" sandstones of Nebraska, Kansas, and 

 New Mexico, a considerable number of angiospermous leaves. 

 Tracings of some of these were sent to Prof. Oswald Heer, at 

 Zurich. He pronounced them of Tertiary age, as he had pre- 

 viously done a series of fossil plants obtained from Vancouver's 

 Island by Dr. Evans, and described by M. Lesquereux. As heavy 

 beds of limestone, containing Cretaceous mollusks, were found by 

 Dr. Hayden and the speaker overlying the Dakota sandstones, it 

 was asserted by us that they must be Cretaceous. 



A lengthy and animated discussion followed in which Prof. 

 Heer, M. Lesquereux, and M. Marcou contended for a Tertiary, 

 Mr. Meek and the speaker for a Cretaceous date. Finally, Prof. 

 Capellini, of Bologna, and M. Marcou went to Nebraska in 1863, 

 and examined some of the outcrops from which the leaves had 

 been taken. Upon their return, they conceded the Cretaceous 

 age of the deposit, and the fossil plants collected by them were 



