OF LOWER GREBNSAND PLANTS. 297 



width, whilst its transverse section exhibits at the centre the 

 same indistinctly cellular appearance as the species last de- 

 scribed ; but near the circumference instead of one it has two 

 laminated circles, and exterior to each of these a narrow land 

 devoid of lamince, analogous to the two bands of cellular substance 

 that are placed in similar relation to the two laminated circles in 

 a recent Cycas." It is curious that this important and interesting 

 feature in the anatomy of the type of Cycadeoidea has been 

 overlooked by writers who discuss the nomenclature of the 

 Cycadophyta as though Bennettites and Cycadeoidea were 

 identical. In Buckland's figure of the external features of 

 Cycadeoidea tnicrophylla there is no sign of cones among the 

 leaf-bases, and there is nothing to show that its fructification 

 resembled that of Bennettites in any particular. 



Nevertheless, many of the u Cycad " stumps from Portland, 

 which later writers have identified as belonging to Buckland's 

 genus, have undoubtedly embedded cones of the Bennettites-' 

 type. These trunks are rightly included in the same genus as 

 Carruthers's Bennettites Gibsonianus, whether it be called Bennet^ 

 tites or Cycadeoidea. The weak point in the argument of those 

 who call these specimens Cycadeoidea is their assumption that such 

 fruiting specimens are really identical with the original trunks 

 described by Buckland, who quite clearly described and illus- 

 trated vegetative features in C. microphylla which differ from 

 those of the Bennettites-tyipe. Under the circumstances it seems 

 to me invalid to identify any fruiting specimen as Cycadeoidea, 

 Buckl. It is clear that the great majority of the Portland 

 (as of the American) trunks are species of Bennettites. 



Owing to the loss of Buckland's type-specimens, and the con- 

 sequent uncertainty regarding their characters, an arguable case 

 might be made out for dropping the generic name Cycadeoidea 

 altogether, though the two specimens about to be described 

 strengthen the arguments for its retention. 



The two species of Cycadeoidea now described both show two 

 or more rings of wood, thus agreeing with Buckland's type 

 and differing from BenneHites. The numerous magnificently 

 preserved American species of Bennettites (named by Wieland 

 1906, etc., Cycadeoidea) show the remarkable uniformity of 

 character in the numerous species of the genus, and the 

 similarity in both vascular anatomy and fructification betweeo 



