Devonian Plants. 9 



3. Prototaxites, gen. nov. (Fig. 4.) 



Woody trunks with concentric rings of growth and medullary 

 rays. Cells of pleurenchyma scarcely in regular series^ thich- 

 walled, and cylindrical^ with a double series of spiral fibres. 

 Disc-structure indistinct in the specimens observed. 



I propose the above generic appellation for a tree having the 

 spirally marked cells characteristic of the genera Taxites and 

 Spiropitys of Goeppert, but differing from any conifer known to 

 me in the cylindrical form and loose aggregation of the wood- 

 cells, as seen in the cross-section, in which particular it more 



Fig. 4 a 





C 



OJD 



OO^ 



gO0 



O..Qytf 



[i:iii'^ri% 



Fig. 5 b 



Fig. 5 c 



Fig. 4. Prototaxites Logani. a, cross-section, magnified 40 diams., 

 showing growth-line and medullary ray ; 6, longitudinal 

 section (300 diams.) ; c, transverse section (300 diams.) 



nearly resembles the young succulent twigs of some modern 

 conifers than their mature wood. A fine silicified trunk of this tree 

 was brought from Gaspe by Sir W. E. Logan, and was shortly 

 described in the ' Proceedings of the American Association ' for 

 1856. 



