AMMONITES — ZOOLOGICAL^ ETC, 



277 



Ammonites Zoologically and Geologically considered. 



(Continued from p. 146.) 



CHAPTER II. 



§ L Critical examination of the number of species amongst 

 the Ammonites. 



By uniting ail tlie names given by authors of all countries 

 to the Ammonites of the cretaceous formations hitherto des- 

 cribed^ I find that prior to the present work 78 species were 

 known. Of this number, nine only {A. Goodhalli, Sow., 

 Concinnus, trisulcosus, Hiatrix, Phill., Stobai, Nilson., verte- 

 bralis, Sow., cinctus, Mantell, and Poly opus, Dujardin), are 

 unknown to me, either from not having been able to obtain 

 specimens, their not being found in France, or lastly that 

 they have been too imperfectly figured to enable me to re- 

 cognise them. I have thus been able to examine compara- 

 tively sixty -nine species of Ammonites noticed or described 

 from the cretaceous formations. On subjecting these spe- 

 cies to a severe revision : 1st as to the synonymes, to correct 

 the double use of different names given to the same Ammo- 

 nite ; 2nd as to the differences caused by the preservation of 

 individuals with or without a shell ; 3rd as to the enormous 

 differences caused by age or sex, which I have pointed out 

 in the former chapter, I am satisfied that out of the number 

 of 69, thirty-eight species, or more than one half, are merely 

 nominal or simple varieties of the others ; and when my 

 analysis was terminated, there only remained thirty-one dis- 

 tinct species out of the 69 which I have had opportunities 

 of personally examining. 



Had I but found these 31 species in France, it would have 

 been considerable as regards the Ammonites known else- 

 where but an appeal to the parties in France, who occupy 

 themselves with geology or interest themselves in the ad- 



u 2 



