IX. 



Professor Blake "On the Bases of the 

 Classification of Ammonites.'" 



THE above is the title of the Presidential Address to the Geologists' 

 Association. No wonder that the members of that association 

 were pleased. Professor Blake is just the man for the task, he is " one 

 of the best geological critics in England " — at least, so we have been 

 told, and we are frequently reminded of the fact ; he has studied the 

 Cephalopoda, and he has written upon them, and treated them from 

 the mathematical point of view ; he is a member of the Council of the 

 Geological Society, and he gave his address as president of the Geolo- 

 gists' Association, No wonder that the members of that association, 

 who were so thankful " for his concise account of one of the most 

 difficult groups of animals — the Cephalopoda " — published last year, 

 should be glad of enlightenment concerning the classification of 

 Ammonites. 



Hitherto the members of the association as a whole have been 

 somewhat at sea about Ammonites. It was a dangerous experiment 

 for one of them to air any of the new (?) generic names in the hearing 

 of his fellows. The powers that be, so he was promptly told, still 

 clung to the good old genus Ammonites, with its six or seven thousand 

 species ; and new generic names were tabooed. No division of this 

 grand old genus could be allowed, even though Professor Blake had, 

 nearly twenty years ago, shown what could be done in the generic 

 division of Ammonites. At last Professor Blake thought the time had 

 come to rescue the members of the Geologists' Association from 

 outer darkness, and accordingly he has once more bravely tackled 

 the question of these new generic names. 



According to Professor Blake the chief bases of Ammonite-classi- 

 fication are four — the form, the size (!), the ornaments, the sutures. 

 He mentions other characters, for instance, the length of the body- 

 chamber, only to dismiss it with the extraordinary remark that " if the 

 interior part of the whorl be occupied by the previous whorl, the loss 

 of space is apt to be made up for by the length of the last chamber ; 

 but no general rule can be laid down." We should think not, except 



1 On the Bases of the Classification of Ammonites. Presidential Address. 

 Proc. Geologists' Association, vol. xiii., part 2, pp. 24-40, 1893. 



