c that I 

 late IX 

 1 Society 



DAWSON — SIGILLARIA, CALAMITE8, AND CALAMODENDRON. 



159 



idodendra with the SifjillaricB of tho Favulnria-ty])s. On the 



er hand, as already stated under Sigillaria, the ribbed Sviillarice 



,ay be related through Ormo,v>flon and Dadoxylon to tho modem 



nifcrs, and the Faindainiv may be related to the Cycads. This rc- 



ioiiship may be expressed as follows: — 



I do not give this Table with any view to theories of derivation, 

 but merely as an expression of probable affinities among tliese very 

 curious and ancient types of vegetation. 



I may add here a few words with reference to Sjdunnplyllmn, a 

 genus which some authors unite with Calamites. 'I no verticillate, 

 Cuneate, veiny leaves of this plant, and its spikes of fructification 

 have long been known ; and in ]8()e5 I was enabled by a specimen 

 in the collection of Sir W. E. Logan to determine the structure of 

 its stem, which contains a slender axis of reticulato-scalariform 

 vessels of the type of those in Tmesipter'n^X . These i)lants obviously 

 had no connexion with Ccdamites or Calamodendron, but constitute 

 a peculiar synthetic type, presenting points of resemblance to Ferns 

 and Marsiliacea). 



In conclusion, and with reference to my former papers on tho 

 ** Structures in Coal," I would repeat the statement made in those 

 papers, that the tissues of ShjiUarla, as defined in this paper, and of 

 Calamodendron enter more largely than any others into the compo- 

 sition of the mineral charcoal, and other parts retaining structure, 

 of the coal of Nova Scotia ; and I have reason to believe that similar 

 tissues arc at least very abundant in the coal of this country. 



Supplementary Note. — Owing to the delay in the publication of the 

 above paper, it is necessary to add the following statements : — 



(1) Trof Williamson has described another type of Calamitean 

 Btcm, which he regards as intermediate between his Cfdamopitus ami 

 Cedamodendron §, but wliich has the retieidated or nudtiporoxs vessels 

 of the former. To Prof, Williamson is due the credit of recogn'-'Mig 

 this structure for the first time in English specimens, though, as lIjvo 



* Inpluding Sagcnaria. t Dawson, MS. 



X Quart. Joiini. Geol. Society. May IHOO. 



i Manchester Lit. and PLil. Soc. rroceedings, 1870. 



llNi* 



