Oh. XXYIL] DISCOVERY OF FOSSIL VERTEBRATA. 539 



10 The fossil monitor of Thuringia (Protorosaurus Spetieri, Y. Meyer) was fig- 

 ured by Spener, of Berlin, in 1810. (Miscel. Berlin.) 



11 See above, p. 506. 



12 Memorabilia Saxonice Subterr., Leipsic, 1709. 



13 History of Rutkerglen, by Rev. David Ure, 1793. 



"'Sedgwick and Murchison, Geol. Trans., Second Ser., vol. iii. p. 141, 1828. 



15 Sir R. Murchison. See above, p. 551. 



16 Mr. Lee, of the Priory, Caerleon (see above, p. 555), found Pteraspis in pres- 

 ence of Mr. Lightbody, F.G.S. 



Obs. — The evidence derived from footprints, though often to be relied on, is omit- 

 ted in the above table, as being less exact than that founded on bones and teeth. 



There are many writers still living who, before the year 1854, 

 generalized fearlessly on the non-existence of reptiles in times ante- 

 cedent to the Permian ; yet in the course of nineteen years they 

 have lived to see the remains of reptiles of more than one family 

 •exhumed from various parts of the Carboniferous series. Before the 

 year 1818, it was the popular belief that the Palseotherium of the 

 Paris gypsum and its associates were the first warm-blooded quadru- 

 peds that ever trod the surface of this planet. So fixed was this 

 idea in the minds of the majority of naturalists, that, when at length 

 the Stonesneld Mammalia were brought to light, they were most un- 

 willing to renounce their creed. First, the antiquity of the rock was 

 called in question ; and then the mammalian character of the relics. 

 But when at length all controversy was set at rest on this point, the 

 real import of the new revelation, as bearing on the doctrine of pro- 

 gressive development, was far from being duly appreciated. 



Their significance arose from the aid they afforded us in estimating 

 the true value of negative evidence, when adduced to establish the 

 non-existence of certain classes of animals at given periods of the 

 past. Every zoologist will admit that between the first creation and 

 the final extinction of any one of the oolitic mammalia now known, 

 whether at Stonesfield or Purbeck, there were many successive gen- 

 erations ; and, even if the geographical range of each species was 

 very limited (which we have no right to assume), still there must 

 have been several hundred individuals in each generation, and proba- 

 bly when the species reached its maximum, several thousands. 

 YYhen, therefore, we encounter for the first time in 1854 two or 

 three jaws of Stereognathus or Spalacotherium, after countless speci- 

 mens of Mollusca and Crustacea?, and many insects, fish, and reptiles 

 had been previously collected from the same beds, we are not simply 

 taught that these individual quadrupeds flourished at the eras in 

 question, but that thousands, perhaps hundreds of thousands, of the 

 same species peopled the land without leaving behind them any trace 

 of their existence, whether in the shape of fossil bones or footprints ; 

 or, if they left any traces, these have eluded a long and most labori- 

 ous search. 



Moreover, we must never forget how many of the dates given in 

 the above table (p. 588) are due to British skill and energy, Great 



