298 DESCKIPTIVE CATALOGUE 



the American and the Eui'opeau species. An exception to the 

 general rule of a single slender woody cylinder in Bennettites is 

 Wieland's Cycadeoidea Jennet/ana (Wieland 1906, p. 78), in 

 which there is a strong woody cylinder " as extensive and 

 compact as that of Cordaites" Unfortunately the illustration 

 given is only a small-scale (reduced by .j) macroscopic photo- 

 graph of the polished trunk-surface, and no microscopic sections 

 appear to be described. So far as can be judged by an examin- 

 ation of Wieland's plate with a lens, I think his alternative 

 suggestion is the correct one, and that 4t there has actually been 

 a persistence of the primary cambium with seasonal augment 

 ation of the secondary xylem." But without microscopic 

 sections nothing definite can be deduced from this most in- 

 teresting form. As the fructifications of C. Jenneyaiui also 

 show some rather important differences from the usual Benin t 

 tites type, it is probable that it should form the basis of a nc\v 

 genus. Its wood, " extensive and compact as that of Cordailett" 

 differs notably both from the single slender cylinder of Ben- 

 nettites and the series of cylinders in Cycadeo'nl>-n. 



Wieland, in a footnote to his p. 78, recognises that anatomical 

 features of this magnitude u are of generic value," and he allows 

 that if the stem-anatomy of Buckland's original Cycad&UUa 

 were shown to differ from that of Benuettites, " then the genus 

 Bennettites is perfectly valid, although for other reasons than 

 those that have hitherto been assigned." A demonstration 

 of essential anatomical differences between Bennettites and 

 Cycadeoidea being now made, it becomes clear that the name 

 Bennettites must be applied to the numerous American specimens 

 of which the well-petrified stems and fructifications are identical 

 with Bennettites in all important respects. 



llegarding the fructifications of the true Cycadeoideas 

 nothing is known. One of the species now described in detail, 

 and originally recorded by Carruthers (1867) as Cycadeoidea 

 Yutesii, was later (1870) put by him in his new genus Yatesia 

 (under the name Yatesia JV/o>vwf), and the genus Yatesia was 

 credited with having " a cone, each carpophyll of which bears 

 two reflexed ovules." The evidence (Jarruthers gives for this 

 (p. 688) appears to me to rest on so many assumptions that it is 

 valueless, his two principal reasons being : 1st, the structure of 

 the stem appears to require deciduous axillary appendages for the 



