448 



PALiEOBOTANY. 



siders that the genus Anfholithcs is in part founded upon 

 tlie spikes of Cordaites, as also the genus Cardiocarpon upon 

 its fruit ; while the pith-cylinders form part of the genus 

 Sternhcrgia, and the genus Dadoxylon simply comprises its 

 woody trunk.-^ 



In addition to the preceding forms, the Devonian rocks 

 have yielded examples of the fossils known as Stcrnhcrgia , 



Fig. 701. — A, Trunk of Fnjtott'.iitis Lnijnni, t'lgliteen inches in diameter, as seen in the cliff 

 near L'Anse Brehaut, Gaspe; b, Two wood-cells showing spiral fibres and obscure pores, 

 highly magnified. Lower Devonian, Canada. (After Dawson.) 



Cyperites, Asterophyllitcs, Annularia, Pinnularia, Cardiocar- 

 pon, and Trigonocarpon. Of these, the genus Sternhergia, 

 comprises cylindrical, transversely-marked fossils, which are 

 now known to be nothing more than the casts of the pith- 

 cylinders of other plants. They seem chiefly to belong to 

 Conifers of the genus Dadoxylon, but they are referable also 

 to Sigillaria, and even to Lcpidodcndron. When the plant 

 to wdiich they belong is itself preserved, there is no difliculty 



1 This is a good instance of the difficulties which attend the study of 

 PalEeohotany, of the extent to which the best authorities are at variance with 

 one another as to the true nature of even widely-distributed genera, and of 

 the depth of the obscurity which still envelops many most important points 

 connected with the structure of fossil plants. 



