8 SIE WILLIAM DAWSON— PAEKA DECIPIENS. 



"Western Canada testify to this in the later Devonian of America, and the Lower Devon- 

 ian Parka affords similar evidence. There is, as I have elsewhere maintained, the best 

 reason to believe that organisms of this kind were also very important in the Carbonifer- 

 ous period, and that many of the sporocarps and macrospores found in the shales, cannels 

 and bituminous coals will prove to be rhizocarpean. In this connection I may also refer 

 to such organisms as Sporocjjslis and Lepidocijitis of Lesquereux, from the coal-formation of 

 Pennsylvania, and which, on the evidence of specimens kindly sent to me by Mr. Lacoe 

 of Pittston, Pa., I am inclined to regard as near allies of Parka. 



The probable relation of Parka with the obscure rugose stems, Zosto-a-like leaves, etc., 

 associated with it in Scotland, also serves to afford at least a conjectural explanation of 

 the quantities of vegetable debris of this kind found in the Erian in Europe and America, 

 and also in some still older formations, and which have variously been referred to Algœ, 

 stipes of ferns, fragments of Lycopodaceous plants, etc. Parka and Protosalvinia also come 

 into connection with PsilophjjLon, PHlopIii/ton, ArthrosUgma and other plants of the Erian, 

 which have been regarded as intermediate between Rhizocarps and Lycopods. 



All these facts place us in presence of a vast development of rhizocarpean forms as 

 forerunners of the abundant and gigantic lycopodiaceous plants and ferns of the latter 

 Palïeozoic, and show that these humble aquatic plants once played a much more import- 

 ant part in nature than one could have inferred from their degraded position in modern 

 times. 



It is due to that gifted observer, the late Sir "W. E. Logan, to recall the fact that his 

 recognition in 1863 of the occurrence of shales filled with " microscopic orbicular bodies " 

 in the Upper Erian of Kettle Point, Lake Huron, described by me, in 1871, as Sporangiies 

 Huronensis, was the first intimation given to the world of the vast deposits of this kind 

 in the Erian of interior America. Another sagacious and acute observer, the late Dr. 

 Fleming, discovered and described Parka decipiens in the Devonian of Scotland, and sug- 

 gested its vegetable nature, as far back as 1831 ; while Miller in later years followed up 

 the research and keiit these obscure fossils before men's minds as probably aquatic plants. 

 In geology it is the men who note and record small and apparently obscure facts who 

 often open the door to wide and important generalizations. Fleming I knew as an aged 

 man when I was a student. Logan and Miller were friends in later years. It is a pleasure 

 to be able to continue and extend their work. 



