APPEAKANCE AND EXTINCTION-. 191 



ly seized hold of by the advocates of the doctrine of independ- 

 ent and successive creations as proving the fallacy of any slow 

 modification theory of transformisin, and were it not that they are 

 in themselves fallacious, would alone be sufficient to overthrow any 

 such theory. For not alone must of necessity the development of 

 a group of forms, all of which were descended from some one pro- 

 genitor, have been an extremely slow process, but the ' ' progenitors 

 must have lived long ages before their modified descendants." The 

 experience of every paleontologist proves to him, however, how 

 misleading are those apparent abrupt appearances, and how very 

 frequently groups of forms, supposed to be restricted to a definite 

 horizon or formation, suddenly appear in a region perhaps not 

 hitherto worked over, or, even where the work of the geologist has 

 been accomplished with a sufficient amount of care, in a horizon 

 of considerably older date. Almost every large group of animals 

 furnishes such instances of antedating. No fact was at one time 

 considered to be more firmly established than that the Mammalia 

 belonged exclusively to the Tertiary and Post-Tertiary epochs, and 

 yet we now know of their existence, even in considerable variety, 

 in the deposits of both Jurassic and Triassic age; the serpents, 

 which until quite recently were thought to have their earliest 

 ancestors in the deposits of the Tertiary age, have been traced 

 back to the Cretaceous (France) ; the Insecta, whose supposed 

 earliest appearance in the Carboniferous rocks was considered to 

 mark an epoch in the faunal development of that period, have, in a 

 series of impressions left in the Devonian shale of New Bruns- 

 wick, proved their existence at a much earlier date, and only with- 

 in the past year, 1884-'85, the announcement is made of the dis- 

 covery of scorpion remains in the Silurian rocks of both Sweden 

 and Scotland. It will still be in the memory of many geolo- 

 gists and paleontologists with what startling effect the announce- 

 ment of the discovery of the first air-breathing vertebrates in the 

 deposits of the coal was made, at the very time when the absence 

 of such forms was ascribed to the impossibility of their breathing 

 an atmosphere supercharged with carbonic acid ! In the case of 

 special genera we have equally well-marked instances of anteda- 

 ting. 



Waagen's discovery of an ammonite in the Carboniferous rocks 

 of the Salt-Range of India was for a long time discredited, so firmly 



