THE FLORA OF THE COAL FORMATION. 



433 



susceptible of rapid decay than most kinds of wood, and too impervious 

 to fluids to be readily penetrated by mineral matter, they were admir- 

 ably fitted for the production of the raw material of coal. 



I have endeavoured to represent the structures above referred to in 

 Fig. 161. 



The species to which I have referred was only one of many more 

 or less resembling it, but differing in details ; and according to these 

 special differences, they may be arranged in the following genera, which 

 may, however, be much modified by the progress of discovery. Op- 

 posite each genus I have given the species representing it in Nova 

 Scotia. 



(1.) Favularia, Sternberg . , , Sigillaria elcgans, Brongn. 



tessellata, Brongn. 



(2.) RiiYTiDOLEFis, Sternberg 



(3.) Sigillaria, Brongn. 



Bretonensis, Dawson, 



scutellata, Brongn. 



Schlotheimiana, Brongn. 



Saullii, Brongn. 



Dournaisii, Brongn. 



Knorrii, Brongn. 



pachyderma, Brongn. 



flexuosa, L. cj- //. ^ 



elongata, Brongn. 



reniformis, Brongn. 



Brownii, Dawson. 



laevigata, Brongn. 



planicosta, Dawson. 



catenoides, Dawson. 



striata, Dawson. 



emiuens, Dawson. 



Menardi, Brongn. 



Sydneusis, Dawson. 



organuni, L. cj* H. 



(4.) Clathraria, Brongn - 



(5.) Leioderma, Goldenb — 



(Asolanus, Wood). 

 (6.) Syringodendron, Steivib. . . — 



Of these, seven are probably new species, and the remainder can 

 be identified with reasonable certainty with European species. The 

 differences in the markings in difTercnt parts of the same tree are, 

 however, so great, tliat 1 regard the greater part of the recognised 

 species of SigiUarice as merely provisional. Even the generic limits 

 may be overpassed when species arc determined from hand specimens. 

 A fragment of the base of an old trunk of Sigillaria proper would 

 necessarily be placed in the genus Leioderma, and a young branch of 



