46 Fossil Fishes. 



" All the species of the genus Cephalaspis have been found in the 

 old red sandstone of England and Scotland. It is not therefore, as 

 has been asserted, in the mountain-limestone, and consequently still 

 less in the Zechstein or Magnesian limestone, that the vestiges of the 

 most ancient fishes have been found. Their presence mounts up to 

 an epoch yet more distant ; for it is now certain that they are found 

 in very considerable number in the old red-sandstone. And moreo- 

 ver, even this formation is not the oldest in which fossil fishes have 

 been discovered. But since the Cephalaspis itself belongs to an 

 epoch so very remote, and since it is of the highest importance for 

 the science of Paleontology to determine exactly the formation in 

 which the first traces of fish are found, I deem it proper now to en- 

 ter into some details concerning all the species of fossil fishes, the 

 debris of which have been discovered in the most ancient beds of the 

 crust of the globe, even although their organization will compel me, 

 in part at least, to postpone their description to the 3d volume of 

 this work. 



"In order that I may be able the better to fix and point out my 

 indications concerning the strata in which the most ancient fish occur, 

 and also that no uncertainty may remain concerning the geological 

 age of their beds, it will be useful here to transcribe in a summary 

 way the results of Mr. Murchison's researches into the fossiliferous 

 stratified rocks below the coal formation — and these indications will 

 be the more exact, inasmuch as it is to Mr. Murchison that I am in- 

 debted for the most of the specimens of fossil fish which I have ex- 

 amined, belonging to formations below the coal measures, and it is 

 also his valuable communications which, in a great degree, have en- 

 abled me to digest this notice In the synoptical table of these stra- 

 tified deposits which Mr. Murchison has published, he commences 

 with the carboniferous limestone, and descends successively to the 

 schistose system of the southern parts of Wales. The English old 

 red-sandstone is the most recent formation whose beds are examined 

 in detail in this table. The upper division of this formation is whol- 

 ly destitute of organic remains.* The whole of these beds, formed 

 of a red conglomerate, and of different sandstones, has a thickness of 

 many thousand feet, as may be ascertained by visiting the escarp- 

 ment — the slopes — of the counties of Brecknock and Caermarthen ; 



* Mr. Murchison has latelj' discovered scales of fishes in the upper part of the 

 old red sandstone. 



