XXXVl] CYCADBOIDEA 385 



hachimia^ was described in the middle of the eighteenth century as 

 a mass of Hijypurites or coral cups : this was found in a swamp in 

 GaUcia and is now one of the most striking objects in the Dresden 

 Museum; a brief account of it is given on page 409. In 1859 

 Tyson discovered two large trunks in the Potomac beds of Mary- 

 land for which Fontaine subsequently proposed the name Tysonia 

 ma/rylandica^, but as Ward pointed out the species is clearly a 

 Cycadeoidea (fig. 507). In 1894 Lester Ward^ recorded several 

 additional stems from Tyson's locahty. It is, however, from the 

 Black HiUs of Dakota, an isolated spur of the Rocky Mountains, 

 formed of older rocks encircled by Lower Cretaceous strata*, 

 that the greatest number of Cycadean trunks have been obtained : 

 the magnificent collection now in the Yale Museum is largely 

 due to the energy and munificence of the late Prof. Marsh. From 

 the Upper Jurassic beds in Carbon Co., Wyoming 5, several stems 

 have been collected, and a prehminary study of their external 

 features led Ward to institute 20 species of a new genus Cycadella. 

 Stems have also been discovered in the Freezout Hills of Wyoming 

 and additional specimens have been found in the Potomac forma- 

 tion of Maryland. The discovery of over 1000 specimens of 

 Cycadean stems in the Lower Cretaceous and Upper Jurassie 

 beds of a few localities in the United States bears striking testi- 

 mony to the abundance of these extinct Gymnosperms during the 

 latter part of the Mesozoic era. It is perhaps true that, as Lester 

 Ward wrote, 'Cycads are to the vegetable kingdom what Dino- 

 saurs are to the animal, each representing the culmination in 

 Mesozoic times of the ruling Dynasties in the hfe of their age®.' 

 Although the number of stems obtained from European countries 

 is relatively small, the abundance of specimens in the Upper 

 Jurassic strata of the Isle of Portland and Northern Italy and 

 their occurrence in Belgium^, France, Germany, Austria, Poland, 

 India and elsewhere, together with an abundance of Cycadean 

 fronds in practically all Jurassic and Lower Cretaceous plant- 

 bearing beds, demonstrate the dominant position of the Ben- 



1 Ward (04); Wieland (08). 



2 Fontaine (89) B. p. 193, Pis. OLXxrv.— CLXxx. •" Ward (942). 



* For an account of the stratigraphy, see Ward (94'). ^ Ward (05) B. 



6 Ibid. (00). ' Coemans (66). 



S. ni 



25 



