Chap. XX.J 
GENEEAL SUCCESSION OF FOEMEE LIFE. 
485 
thousands of feet thick, and scarcely at all altered, which, made up of 
sand, mud, and pebbles, constitute the very foundation of the fossil- 
bearing Silurian strata. In these huge lower sediments, only a doubt- 
ful genus of Zoophyte with traces of Annelides or Worms have been 
found, and portions of a Trilobite (p. 28) ; whilst chemical analysis has 
afforded independent proofs that phosphoric acid, a true indicator of former 
life, is hardly to be detected in these rocks, though it abounds in the 
fossiliferous Silurian strata. If this argument were derived from the evi- 
dences collected in one region only, it might have been suggested that, as 
the same formation which is barren in life over one district teems with 
signs of it in another, so the Cambrian rocks elsewhere may still prove to 
be more fossiliferous ; but such infra- Silurian rocks have been well ex- 
plored in many countries, and even when unaltered have not yet afforded 
the scanty signs of life which have been wrung from them in Britain. 
Lastly, the discovery of the little Foraminifer Eozoon in the Laurentian 
rocks strengthens prodigiously the other inferences previously arrived at 
by evidence from so many parts of the earth, knowing as we now do that 
the lowest grade of animal has alone been detected in the oldest of all 
rocks. Be it also recollected that this, the only additional evidence ob- 
tained in this branch of our inquiry during the last seven years, supports 
the view of successive creation which I have long maintained. 
When we proceed upwards into the Lower Silurian strata, replete with 
clear and well-defined groups of all marine animals except Yertebrata, an 
antagonist might possibly reply that Gelatinous Fishes, devoid of backbones 
(like the solitary little Amphioxus now living), may have been the only 
creatures of their class which swarmed in the then existing seas, — and, 
if so, that no traces of them were likely to exist, their boneless bodies 
perishing and leaving no sign of their former existence. As an old student 
of Nature's works, I cannot, however, allow this hypothesis to outweigh 
the numerous well-recorded facts which announce the coexistence and 
perfection of all the other classes in the ancient marine areas. If thou- 
sands of invertebrate animals have left their coverings behind, and the 
most delicate impressions of their parts, is it rational to suppose that, if 
Fishes then existed, every part of their framework should be wanting 
which, whether consisting of dermal plates or of vertebrae, characterizes 
them in the strata of all succeeding epochs ? Nay, more, we have even in 
the Silurian strata fossil reliquiae of such soft animals as Starfish ; and if 
so, why not those of the imaginary boneless fish of the theorist ? But the 
stony records are not silent as to what were the predaceous animals of the 
ocean before the creation of Fishes, properly so called ; for we see that in 
this same long period, in which no traces of Yertebrates prevailed, there 
was an abundance of Cephalopods ; and as creatures of that structure 
are well known to be carnivorous, we have a fair right to assume that 
they were the appointed tyrants of those Silurian seas.. 
