﻿CHAPTER VI. 



OVULATE CONES.* 



HISTORICAL. 



The silicified trunks of Mesozoic cycads, as noted in the introductory chapter, 

 have been known for more than a century, while their earlier scientific study was 

 begun fully seventy-five years since. But the true nature of the majority of these 

 trunks was for a long time scarcely suspected. In 1S56 or 1857, however, there 

 was collected in the Lower Greensand at Luccomb Chine, in the Isle of Wight, a 

 remarkable silicified trunk of far more importance than any previously discov- 

 ered. For, a dozen years later, when studied in thin sections — doubtless the 

 first ever made from fossil cycads — this specimen was discovered by William Car- 

 ru thers to bear laterally, in the axils of its old leaf bases, numerous marvelously 

 preserved, bract-inclosed ovulate fruits of ovoid shape and widely different structure 

 from those of any other known cycadaceous plants, living or extinct. The essential 

 structural features of the trunk, and of the fruits it bears, were described in 1S69 

 under the name of Bennettites Gibsonianus in Carruthers' important memoir on 

 Fossil Cycadean Steins from the Secondary Rocks of Britain (24). 



Subsequently, Count Solms-Laubach restudied the preparations of Carruthers, 

 he himself making additional thin sections from the type specimen. He added 

 certain details concerning the "seed-stems" and " iiiterseminal scales," and discov- 

 ered the dicotyledonous embryos, the first observed in any fossil plants (156). 



Later still, Lignier (82) studied the dehiscent fruit originally found by Moriere 

 in the Oxfordiau Jurassic of Vaches-Noires (falaises de Villers-sur-Mer), Calvados, 

 Normandy, in 1865, and which had in 1881 been made the type of WUliamsonia 

 Moricrei by Saporta and Marion. The microscopic features of this fruit, which 

 is generically if not specifically allied to Bemic/lites Gibsonianus^ and of the same 

 general type as Cycadcoidca Wielandi Ward, are preserved in iron carbonate with 

 marvelous delicacy of detail, as described in Professor Liguier's memoir with that 

 completeness and exactness which might be asked in the case of a living form. 



The next contribution to the subject of ovulate fructification in the Cyca- 

 deoidea; was made by the writer in 1899 as one of the results of the preliminary 

 structural study of the remarkable Black Hills series of silicified cycads (189). A 

 large number of these trunks were found to bear ovulate fruits of various new 

 species or genera of the Bennettites Gibsonianus and B. Moricrei type, in far greater 

 profusion than had been previously observed, the histologic structure also being in 



*Were it not for the fact that the younger cycadeoidean fructifications can only be readily under- 

 stood after consideration of maturer forms, it would have been deemed preferable to depart from the 

 order of study and take up the subjects of Chapters VI-VIII in the normal or botanical sequence — young 

 fructifications, bisporangiate or pollen-bearing axes, and ovulate fructifications. 



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