62 THE GEOLOGICAL HISTORY OF PLANTS. 



abundant, in the Carboniferous. Many years ago I ob- 

 served, in a beautiful specimen collected by Sir W. E. 

 Logan, in New Brunswick, that the stem of this plant 

 had an axis of reticulated and scalariform vessels, and an 

 outer bark.* Eenault and Williamson have more recently 

 obtained more perfect specimens, and the former has 

 figured a remarkably complex triangular axis, containing 

 punctate and barred vessels, and larger punctate vessels 

 filling in its angles. Outside of this there is a cellular 

 inner bark, and this is surrounded by a thick fibrous en- 

 velope. That a structure so complex should belong to 

 a plant so humble in its affinities is one of the strange 

 anomalies presented by the old world, and of which we 

 shall find many similar instances. The fruit of Spheno- 

 pJiylhtm was borne in spikes, with little whorls of bracts 

 or rudimentary leaves bearing round sporocarps. 



Fig. 17. — Ptilophyton plumosum (Lower Carboniferous, Nova Scotia). 

 Natural size and magnified. 



A second type of plant, which may have been Ehizo- 

 carpean in its affinities, is that to which I have given the 

 name Ptilophyton.\ It consists of beautiful feathery 



* "Journal of the Geological Society," 1865. 

 f Plumalina of Hall. 



