THE HISTORY OF PLANT LIFE. 33 



of leaf-like bodies similar to those of Marsilia seems to suggest 

 the possibility of foliage of that type. Our present knowledge, 

 however, centers in the carbonized discs, from which important 

 data have been obtained. Boiling them out in nitric acid they 

 yield two kinds of spores. The macrospores measure 40 /* in 

 diameter and are therefore slightly larger (34 /u) than the spores 

 of Lycopodium. The somewhat elongated microspores are 1 5 p 

 in diameter. In addition, there are to be found numerous 

 compound cellular bodies with a central carbonized mass. 

 The obvious remains of spores, from which as a center there 

 extends a tissue in various stages of development, leave no 

 doubt as to the fact that these structures represent prothalli in 

 various stages of growth. From these facts the conclusion is 

 a direct and justifiable one that Parka was a heterosporous 

 plant with its separate male and female sporangia enclosed in 

 a common sporocarp, and therefore comparable among modern 

 plants with Pilularia. Beyond this nothing definite can be 

 stated, hence for the present the specific name decipiens, as 

 originally applied by Fleming, is retained. 



In 1855 Sir William Dawson discovered, in the Devonian 

 sandstones of Gaspe, the remains of a gigantic alga, to which 

 he subsequently gave the generic name of Nematophyton. Since 

 then plants of the same type have been found in Germany, 

 England, Scotland, and various parts of the United States, 

 thus indicating the very wide distribution of plants having a 

 common ancestry. At the present time, for purposes of con- 

 venience, eight different species are distinguished, but it is 

 altogether probable that these may in reality represent only 

 four separate species at the most. 



As represented by specimens of N. Logani in the Peter 

 Redpath Museum of McGill College, these plants were some- 

 times eighteen inches to two feet or more in diameter, and 

 specimens recently found in New York State show a recover- 

 able length of twenty-four feet. These facts seem to indicate 

 that the complete plant attained to great size, far exceeding 

 anything known among the arborescent forms of algae at the 

 present day. No foliage or fruit has been found, and our 

 knowledge of these plants rests entirely upon the details of 



