1881. J ^OJ [Lesquereux. 



in the centre by small pores or inclined fissures, which, by contraction or 

 widening, become elliptical or round. In badly preserved or old specimens 

 the pores occupy nearly the whole space of the areoles. 



The characters of the wood of Gordaites as exposed above are much like 

 those of the wood of some Conifers, and from this aflQnity, the fossil frag- 

 ments of wood or trunks discovered in the Devonian and the Carboniferous, 

 have been generally referred by authors to Conifers. Dadoxylon Endl., 

 Araucarites Gcepp., Pinites Lind. and Hutt. are all referable io Gordaites. 

 It is now well known that Lomatophloios, to which Corda referred the me- 

 dullary cylinder of Artisia, has a far different kind of pith. 



Considering especially the structure of the trunks of Gordaites and the 

 character of the fructifications, Prof. Renault finds a relation between 

 these plants and the Gycadece, from which they greatly differ, however, 

 by their mode of growth and stature. The disposition of the flowers has 

 some analogy with that of the Taxinece or Oenetacem. 



The PoroxylecB do not offer any remark applicable to what is known of 

 fossil plants of this continent. They are represented by fossil trunks, of 

 which three species are described by the author. 



The Sigillarm and the StigmaricE; on the contrary, are of peculiar interest 

 on account of the great abundance of their remains disseminated over and 

 in the whole thickness of the American Coal measures, sometimes constitu- 

 ting whole strata of combustible mineral. 



Prof. Renault finds, in the wood of Sigillarim, medullary raj'S, an endog- 

 enous and an exogenous zone, and vasculur fascicles originating between 

 the zones and constituting the strings of vessels entering and composing 

 the leaves. These characters relate them to phanogamous gymnosperms. 



From anatomical researches, Brongniart had coine to the same conclusion, 

 which is supported also by Saporta and Grand 'Eury. On the contrary 

 Profs. Hooker, Williamson, Binney of England, who have pursued re- 

 peated observations and made numerous and very careful anatomical 

 analysis of the wood of Sigillarice, find in it the characters of Lycopo- 

 diaceous plants, and relate them to Lepidodendron. 



The discordance of views may result, as supposed by Prof. Renault, 

 from the difference of age of the plants from which were derived the 

 specimens subjected to analysis. But the supposition is strongly contra- 

 dicted by Prof Williamson in a recently published paper, on the organi- 

 zation of the Fossil Plants of the Coal measures.* To follow the details 

 of the discussion on this very interesting question it would be necessary to 

 have the illustrations under the eyes. 



We have no means of comparing the determination of the celebrated 

 authors. All that I know and can see from American specimens of the 

 outside characters of Lepidodendron 0.116. Sigillaria indicates a close typical 

 relation of both genera, and therefore in the U. S. coal flora I have placed 

 the genus Sigillaria in the Lycopodiacece. 



Stigmaria necessarily follow Sigillaria ; for remains of Stigmaria have 



* Proc. of the Royal Soc, No, 205, 1880, 



