BENNETTITEAE 559 



trunk of Cycadeoidea marylandica, the first American 

 Cycad to be discovered ; it was found about the year 

 i860, between Baltimbre and Washington, by the 

 geologist Philip Tyson. Many years elapsed before 

 any further discoveries were made ; it was not till 

 1893 that additional specimens came to light in 

 Maryland and that the rich deposits of the Black 

 Hills of Dakota began to be explored. 



The vast majority of the Mesozoic Cycadophyta at 

 present investigated differ essentially from the existing 

 Order Cycadaceae, and have been grouped under the 

 family name Bennettiteae or Cycadeoideae. 



1. Bennettiteae. — In a great number of cases, 

 fructifications have been found in association, or, 

 more often, in actual connection, with the stems of 

 Cycadophyta, and it is only in the rarest instances that 

 these fructifications have proved to be of the Cycadean 

 type, as known to us from its recent representatives. 

 In an overwhelming majority of the fructifications 

 belonging to the Mesozoic Cycadophyta (using that 

 form of name, as suggested by Professor Nathorst, to 

 indicate a group enormously wider than our recent 

 Cycadaceae), the structure of the organs of reproduc- 

 tion is found to have been totally different from 

 anything known in the recent Order, and of a far 

 more highly differentiated type. The' main purpose 

 of the present chapter is to give some account of these 

 plants, which formed the dominant group of Cycado- 

 phyta in the Mesozoic period. 



The family in question is that of the Bennettiteae, so 

 named from the type-genus Bennettites, founded by Mr. 



