APPENDIX. 



281 



ginning of the Upper Silurian, or even as low as the Hudson River 

 group, and Hicks has found Nematophyton and Psilophyton in beds 

 about as old in Wales, along with the uncertain stems named Ber- 

 wynia. In the Lower Silurian the Protannularia of the Skiddaw 

 series in England may represent a land-plant, but this is uncertain, 

 and no similar species has been found in Canada. 



The Cambrian rocks are so far barren of land-plants ; the so- 

 called Eophyton being evidently nothing but markings, probably 

 produced by crustaceans and other aquatic animals. In the still 

 older Laurentian the abundant beds of graphite probably indicate 

 the existence of plants, but whether aquatic or terrestrial it is impos- 

 sible to decide at present. 



It would thus appear that our certain knowledge of land- vegeta- 

 tion begins with the Upper Silurian or the Silurio-Cambrian, and 

 that its earliest forms were Acrogens allied to Lycopods, and proto- 

 typal trees, forerunners of the Acrogens or the gymnosperms. In 

 the Lower Devonian little advance is made. In the Middle Devonian 

 this meagre flora had been replaced by one rivalling that of the Car- 

 boniferous, and including pines, tree-ferns, and arboreal forms of 

 Lycopods and of equisetaceous plants, as well as numerous herba- 

 ceous plants. At the close of the Erian the flora again became 

 meagre, and continued so in the Lower Carboniferous. It again be- 

 came rich and varied in the Middle Carboniferous, to decay in the 

 succeeding Permian. 



II. — HEER'S LATEST RESULTS IN THE GREENLAND 

 FLORA. 



A very valuable report of Prof. Steenstrup, published in Copen- 

 hagen in 1883, the year in which Heer died, contains the results of 

 his last work on the Greenland plants, and is so important that a 

 summary of its contents will be interesting to all students of fossil 

 botany or of the vicissitudes of climate which the earth has under- 

 gone.* 



The plant-bearing beds of Greenland are as follows, in ascending 

 order : 



1. Cretaceous. 



1. The Kome series, of black shales resting on the Laurentian 

 gneiss. These beds are found at various other localities, but the 



Meddelelser om Gronland, Hefte V., Copenhagen, 1883. 



