134 BENNETTITES. 



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Genus BENNETTITES, Cairuthers. 



[Trails. Linn. Soc. vol. xxvi. 1870, p. 681.] 



In 1855 the President of the Linnsean Society of that year, 

 Robert Brown, exhibited a new form of cycadean stem which 

 had been found by Saxby at Bonchurch, in the Isle of Wight. 1 

 The name Cycadites Saxbyanus was suggested by Brown for this 

 new fossil, of which the two most striking features were the 

 elliptical outline of the stem as seen in transverse section, and 

 the presence of a bud in the axil of each leaf. Fifteen years 

 after the discovery of this stem, Carruthers 2 published a full and 

 scientific description of several examples of the same species. 

 As a result of careful investigation of the morphology of these 

 specimens, Carruthers instituted the generic name Bennettites 

 for the new form of stem, which he found could not be classed 

 under any of the recognized subdivisions of the Order Cycadacece. 

 After speaking of the elliptical form of the axis and the presence 

 of buds in the axils of many of the leaves, Carruthers proceeds 

 to describe the anatomical structure of the stem, and calls special 

 attention to the leaf-traces as affording another characteristic 

 feature of the genus. " In all the known members of the Order 

 (Cycadacea)" 3 says Carruthers, "the leaf-traces arise in the 

 interior of the cylinder of wood, as bundles of small size, and, 

 passing through the meshes of the ligneous cylinder, and then 

 through the cortical parenchyma, as small distinct bundles, after 

 running for a short distance, at least in some genera, in a 

 horizontal direction parallel to the periphery of the stem, they 

 pass in the petiole of the leaf." In Bennettites, however, "the 

 vascular tissue for each leaf springs from the woody cylinder in 

 a single large compact bundle, which as it passes outwards breaks 

 up into the different bundles required for the service of the leaf." 

 This peculiar behaviour of the leaf-traces is also referred to 

 by Solms-Laubach 4 as an important distinctive character of 



1 Brown, p. 130. 



2 (I)- 



s Ibid. 



* (2), p. 422. 



