6 DB. HOOKEK AND DB. THOMSON'S PRiECTJBSOBES 



• 



• 



the limits of such a group as Codonopsis and its allies; and 



M 



rank 



our 



their structural peculiarities. Indeed we have little doubt that, 

 could we undertake a revision of the whole Order, these and many 

 other of the present genera would be reunited as subgenera of 



larger groups. 



Upon this subject we take the liberty of reading a note on the 

 principles upon which genera should be established in Botany, 

 communicated to us by Mr. Bentham, who has kindly embodied 

 the views which we hold in common with him, in a memorandum 

 appended to this communication. 



The genera of Campanulacecd are indeed, for the most part, qmte 

 artificial ; and of this the best proof we can offer is to be found m 



Codonopsis, 



already 



connected by natural 



colour 



ip 



doubted ; but some of them present more striking differences from 

 one another, and more remarkable deviations from the common 

 plan on which the Order is constructed, than any other plants in it. 

 By far the greatest peculiarity is exhibited by Campanvmosa and 

 Cyclocodohy genera which present the paradox of a calyx mferus 

 and a corolla supera. In Cyclocodon this anomaly is carried to 

 the highest degree, the sepals being in C. parviflorum placed on 



peduncle of 

 lla and ovary 

 adhere to tl 



So remote 



from one another are the points of insertion of the calyx and 

 corolla in both these instances, that the sepals have been de- 

 scribed as leaflets of an involucre, though their development is 

 opposed to this conclusion, and their sestivation is normally val- 

 vate. In Codonopsis the calyx is adherent to the base of the 

 ovary, and the coroUa is inserted at the point where the lobes 

 of the calyx are given off: but so similar in other respects is one 



^ this eenus to one of Camnanumrpta f.hat.thev can with 



difficulty be distinguished, except by a close comparison : 

 these last-named genera again differ wholly from Cyclocodon in 

 their ramification, large tuberous roots, twining stems, and fc?tid 

 milky juice. ^^ 



Sec p. 30 of this voUmie. 



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