THE LOWER SILURIAN PERIOD. 



97 



Of the life of the Lower Silurian period we have record in a 

 vast number of fossils, showing that the seas of this period 

 were abundantly furnished with living denizens. We rte!ve, c 

 however, in the meanwhile, no knowledge of the land-surffeces" 

 of the period. We have therefore no means of speculaitlng 

 as to the nature of the terrestrial animals of this ancient -age, T 

 nor is anything known with certainty of any land-plants which 

 may have existed. The only relics of vegetation upon which 

 a positive opinion can be expressed belong to the obscure 

 group of the " Fucoids," and are supposed to be the remains 

 of sea-weeds. Some of the fossils usually placed under this 

 head are probably not of a vegetable nature at all, but others 



Fig. 36. Licrophycus Ottaivaensis, a " Fucoid," from the Trenton Limestone 

 ^Lower Silurian) of Canada. (After Billings.) 



(fig. 36) appear to be unquestionable plants. The true affin- 

 ities of these, however, are extremely dubious. All that can 

 be said is, that remains which appear to be certainly vegetable, 



