34 SCIENCE PROGRESS. 



anything", more marked in the internal structure than the 

 external form ; so, that even when agreement in form fails, 

 similarity in structure which is all important remains. This 

 cannot be said of the Otites and Cardites. 



The argument is then pushed a step farther by pointing 

 out that the resemblance between organism and formed 

 stones is frequently not so close as is asserted : thus the 

 Cornua Ammonis had been likened to the shells of Nautilus 

 from which they certainly differ in important particulars ; 

 but in addition to these minor points of difference Dr. Plot 

 triumphantly cites instances in which they had been ob- 

 served with "heads". "' Vidimus enim lapidem hinc de- 

 latum surpentis in spiram revoluti effigie, cujus caput in 

 circumferentia prominuit, extrema cauda centrum occu- 

 pante,' are the very words of Mr. Cambden". 



Although this instance is an unfortunate one, since the 

 " heads " were no doubt the work of some practical joker or 

 fraudulent fossil finder, yet the argument will not be greatly 

 affected, since it is admitted that the fossil forms often 

 differ markedly from their living representatives. The 

 explanation of these differences had been arrived at long 

 before by Palissy, and is suggested by a writer, bearing the 

 illustrious name of Lister, who says truly that these fossils 

 must be either "terrigenous, or if otherwise, the animals 

 they so exactly represent have become extinct ". Referring 

 to this Dr. Plot remarks : " If it be said, that possibly these 

 Species may be now lost, I shall leave it to the Reader to 

 judge, whether it be likely that Providence, which took so 

 much care to secure the works of the Creation in NoaJis 

 Flood, should either then, or since, have been so unmindful 

 of some Shell-fish (and of no other Animals) as to suffer 

 any one Species to be lost ". 



Since this was written we have learnt to accept the 

 doctrine of the extinction of species ; it has become a 

 common-place amongst the educated, and has passed into 

 the language of our poets : — 



So careful of the type she seems ! But no ! 

 From scarped cliff and quarried stone 

 She cries a thousand types are gone ! 

 I care for nothing ; all shall go. 



