THEIR VALUE IN DETERMINING GENERIC AFFINITIES. 165 



What is their evidence worth ? 



I would venture to submit that — 1st. The arrangement of the 

 fiibro-vascular bundles should be taken into account in the deter- 

 mination of genera — especially where the accepted characteristics 

 fail to establish the position. 



2nd. The gradation from one arrangement of these bundles to 

 another, so marked at greater intervals, so slight at successive 

 stages, asks for recognition in an arrangement of genera correspon- 

 dent to this development. 



The sections illustrative of these observations are in the cabinet 

 of the Club. 



Journ. Q. M. C, Series II., No. 4. o 



