PRODROMITES, A NEW AMMONITE GENUS FROM 

 THE LOWER CARBONIFEROUS 



CONTENTS 



Occurrence of Paleozoic Ammonites. 



Genus : Prodromites Smith and Weller, gen. nov. 

 Prodromites gorbyi (Miller). 



Prodromites praematurus Smith and Weller, sft. nov. 

 Conclusion. 



Occurrence of Paleozoic Ammonites. — Until twenty-five years 

 ago it was thought that the ammonites were confined entirely to 

 the Mesozoic, and that the Paleozoic representatives of the 

 Ammonitoid group were all goniatites. This was in keeping with 

 the theory that ammonites all belonged to a single stock or 

 phylum. But the discovery in the Salt Range Permian of sev- 

 eral genera of different stocks that could not, by any stretching 

 of the name, be called goniatites, upset this idea. For a long 

 time after this the Permian ammonite fauna of India was looked 

 upon as exceptional until the recognition of the Permian age of 

 the ammonite fauna of the Artinsk beds of Russia. This was 

 followed shortly by the discovery of similar forms in strata of 

 the same age in Sicily and in Texas. It was then universally 

 recognized that these forms were not exceptional, and might be 

 looked for wherever the uppermost Paleozoic was found in its 

 marine facies. But even as late as 1891 we find the Permian 

 ammonite species of Texas described as Mesozoic types occur- 

 ring in Paleozoic beds, and in all text-books even today the 

 Permian epoch is given as the period of transition from gonia- 

 tites into ammonites. 



Steinmann and von Sutner 1 were the first to attempt to divide 

 the ammonites into various phyla, derived from separate stocks of 

 goniatites, and while their classification is not always in agree- 

 ment with the most rational arrangement, it is very suggestive, 



'Steinmann: Elemente der Palaeontologie, 1S90. 



255 



