26 THE AMERICAN MONTHLY [Jan,, 



The shale in which these discs were found contained 

 bituminous matter and burned with much flame. There 

 were also other small particles which were believed to 

 be stems of a species of calamites or fossil seeds. 



In 1882, Prof. Edward Orton, of Columbus, Ohio, re- 

 ported the finding of similar bodies in the Erian and 

 lower Carboniferous shale of Ohio. At the same time 

 Prof. Williams said he had found similar bodies in the 

 Hamilton shales of New York. Prof. J. M. Clarke, of 

 Northampton, Mass., subsequently reported the presence 

 of similar bodies in the Genesee shales and the Carbo- 

 niferous limstone. No certain clew, however, enabled 

 Prof. Dawson to place them definitely in the flora of 

 this early age. In March, 1883, specimens were found 

 again in the Erian formation of Brazil, South America, 

 by Orville Derby, which throw new light on the subject. 

 These were found to contain along with Sporangites, 

 abundant fronds of Spirophyton. The Sporangites of 

 Brazil resemble in every respect the involucres or spore- 

 sacs of modern rhizocarps, and especially the sporocarps 

 of the genus Salvinia, (a genus of the order of Hydrop- 

 terides related to the club-moss family). 



Quillwort is found on the bottom of ponds in New 

 England, and Azolla is found in pools and lakes in New 

 York to Illinois southward. Salvinia natans was said by 

 Purch to be found growing on the surface of small lakes 

 in western New York, but has not been found by any 

 other person, and probably does not occur in this coun- 

 try, but the spores of Azolla can be taken as represent- 

 ing those of Salvinia, although they are covered with 

 hairs whilst Rhizocarps are apparently smooth. The 

 Azolla is much like a floating Liverwort and perhaps 

 came by evolution from that plant. At all events spores 

 of Salvinia are Rhizocarps and look like brownish bodies 

 lense shaped and with a double outline. They have no 

 marking upon them, but look like little round balls. 



