VOL. IX, pp. 75-88 APRIL 9, 1894 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



FOSSIL CYCADEAN TRUNKS OF NORTH AMERICA, 



WITH A REVISION OF THE GENUS 



CYCADEOIDEA BUCKLAND. 



BY LESTER F. WARD. 



The recent discovery of a large number of fossil cycadean 

 trunks in the Cretaceous rim of the Black Hills, has furnished 

 a new stimulus to the study of these forms in America. Such 

 objects have been found at no less than six distinct North Ameri 

 can localities. The oldest and best known forms are those first 

 mentioned by Tyson from the Lower Cretaceous of Maryland. 

 Dr. Emmons found one such in the Trias of North Carolina, and 

 Sir Wm. Dawson another in the Trias of Prince Edward Island. 

 All the rest, with one exception, are from Cretaceous strata, the 

 age probably not widely differing from that of the Maryland 

 specimens. These are from the Trinity division of the Comanche 

 group in Southern Kansas, and from two localities among the 

 foot-hills outside of the Red Beds of the Black Hills region in 

 South Dakota. The exception to this is the Cycadeoidea mira- 

 Mlis (Lx.) Solms (Zamiostrobus mirabilis Lx.), found on the 

 surface of the ground by Dr. F. V. Hayden, near Golden, Colo 

 rado, within the Laramie, or Post-Laramie terrane. This locality 

 is at the foot of the Front Range, and it would have been very 

 easy for an erratic block to be borne down the mountain side and 

 lodged in the valley where this was found. As is well known, 

 older formations are encountered on ascending the eastern slope 



