JEFFREY. — VRArC.VRIOXYLON TYPE. .")()1 



largr miiiihrr of Arauciirian forms, which apparently hocjiinc extinct 

 Avitli the close of the Mesozoic. 



As a consequence of the investigation of the normal and traumatic 

 occurrence of resin canals in the wood of the Araucariineae, li\ing 

 and extinct, the conclusion seems clear, that this tribe of conifers 

 once possessed li<,Mieous resin canals as a normal feature and there is 

 thus added one more argument for deriving them ancestrally from the 

 Ahietineae and not directly from the Cordaitales, as is commonly held. 

 This view of the matter is strongly supported by the data described 

 in the previous article, in connection with the pitting of the tracheitis 

 and the distribution of bars of Sanio. It is likewise confirmed by the 

 evidence as to the ancestral character of the ray structure in the 

 Araucarian tribe, which strongly resembled that found in the Ahie- 

 tineae, past and present. The ancestral occurrence of wood paren- 

 chyma in the Araucarian tribe is likewise a strong argument against 

 their inunediate connection with the Cordaitean forms and indicates 

 that they in common with the conifers in general, with diffuse wood 

 parenchyma are of relati^■ely recent origin compared with the Ahie- 

 tineae, which in so many ways show themselves to be a very ancient 

 group. 



Summary. 



1. Certain Mesozoic woods from the Jurassic and Cretaceous, 

 showing traumatic resin canals are of xAraucarian affinities. 



2. This is shown to be the case by the structure of their tracheids, 

 both as regards pitting and the absence of cellulose bars of Sanio. 



3. Abietineous pitting in the rays of extinct conifers is not in itself 

 a character of sufficient constancy to serve as a reliable diagnostic 

 feature, since pitting of this type can readily be produced as the result 

 of injury and moreover is often normal in the more conservative 

 parts of living representatives of the Araucariineae. 



4. Xormal resin canals occur embedded in the primary xylem of 

 the traces leading to the abortive cone-scales attached to the peduncu- 

 lar region of the cone of Agaihis B'uhclllii. 



5. This fact taken together with the traumatic phenomena pre- 

 sented by certain Mesozoic Araucarian woods, supplies an additional 

 argument for the derivation of the Araucariineae from an Abietineous 

 ancestry. 



