22 INTRODUCTION. 
British species may even represent two different genera ; the Oldhamia antiqua of Forbes 
being the Murchisonites antiquus of Goéppert.’ Subsequently another organism, called 
Hozoén Canadense, classed with the Foraminifera, and allied to Tinoporus of the 
Nummuline Group, has been discovered in the Lower Laurentian Rocks of North America, 
which, as far as all researches go, constitute the fundamental strata in the crust of the globe. 
Wedded to no theory, and guided solely by an appeal to facts, I have not passed 
the better half of my long life in exploring the foundation-stones of the earth without 
being led to recognise, in the successive works of Nature, the clearest proofs of creative 
power, as manifested by the appearance in each succeeding deposit of animals specially 
adapted to the conditions of each geological period. 
Thus, in those very fundamental strata, wherein igneously formed or molten matter is 
associated with the once muddy or sandy layers accumulated in the seas of that pristine 
period, now in the state of gneiss, geologists who, up to the time of the recent discovery, 
believed these rocks to be azoic, or void of traces of life, now know that nothing distinct has 
heen discovered save a low form of Protozoon, or Foraminifer of the class Rhizopoda.’ 
In the next overlying group, or Cambrian, we find, besides the Zoophyte Oldhamaa, 
the remains of Annelids or Sea-worms, of the genera called Histioderma, Chondrites, 
&c., with the single doubtful Crustacean termed Pal@opyge. In the Cambrian, there- 
fore, a slight advance only im the forms of life is apparent; but no sooner do we 
proceed upwards into the accumulations of detrital matter which were next added to the 
crust of the earth, z. e., the Lower Silurian, than we meet with marked additions in the 
presence of both Mollusca (especially Brachiopoda) and Crustacea, associated with much 
more complex Zoophytes, or Corals, than those of the older rocks. These, with certain 
Cephalopoda, Heteropoda, Pteropoda, and Annelida, constitute the entire Fauna of the 
Lower Silurian Rocks, in which the closest researches of the last quarter of a century have 
failed to detect any remains of Fishes, or the lowest class of Vertebrata. For in the 
median or Llandovery Group, and even throughout two thirds of the Upper Silurian Rocks, 
notwithstanding the great increase of other marine animals, still we find no remains 
of Fishes, and it is only on reaching the Upper Ludlow Rocks, and specially in 
those beds which pass upwards into the Devonian System, that the relics of Fishes have 
been found. ‘These were described by me in my earliest work, in which it was announced 
that the Fishes of that epoch first “appeared before naturalists as the most ancient beings 
of their class,”* and such they still remain. In the forty years which have elapsed since 
these words were printed, they have never been gainsaid; and hence those authors 
eminent as they are, who have laid it down in their tables, that Fishes appeared at the 
same time as the invertebrate orders of animals, are directly in antagonism to the results 
1 Flora Sil. Dev. Unter-Kohl., pl. 34, f. 1-2. 
2 This is under the supposition that, with Dr. Carpenter and others, we reject the validity of the efforts 
which have been recently made to show that the so-called Hozdon is not an animal but a mineral substance. 
§ Silurian System, p. 605: see also note. 
