THE LOWER SILURIAN. PERIOD. C7 
Of the Zfe 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 have, 
however, in the meanwhile, no knowledge of the land-surfaces 
of the period. We have therefore no means of speculating 
as to the nature of the terrestrial animals of this ancient age, 
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 
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f f YJ .»** 
i / Ui, 
/ Y 
j GY, 
Y 
Uf 
SF 
i a 
IM 
Poyalvry, / 
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Fig. 36.—Licrophycus Ottawaensis, 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 ig, that remains which appear to be certainly vegetable, 
‘ G 
