METAMORPHOSIS OF AMMONITES. 97 



repose, that, in accordance with the old conchological 

 practice, they would be unreservedly claimed as species, 

 if the connecting links were not too conspicuous and the 

 territory too circumscribed, and if the geological period, 

 which must, however, be reckoned at least by thousands 

 of years, were not considered too insignificant. 



But what the case of Steinheim exhibits in miniature 

 was taking place on a large scale during the great geo- 

 logical periods, and the zeal of some Palaeontologists, 

 such as Waagen, Zittel, Neumayr, Wiirtenberger," has 

 had the effect of proving, at least with respect to the 

 important division of the Ammonites, the utter impossi- 

 bility of separating them into " species." The study 

 of Ammonites has shown that from fossil remains 

 important inferences may be made as to the whole 

 organization, and that, in combination with the observ- 

 able modifications of the shell, simultaneous and pro- 

 found metamorphoses of certain determining soft parts 

 must have taken place. If it is now proved, as it has 

 been by these investigators, that the so-called " species " 

 which characterize the great Jurassic and cretaceous 

 formations, are connected in the same manner as 

 the varieties of the Steinheim snail, as mere morpho- 

 logical series of variable constancy and duration, they 

 who will not allow even this evidence to rouse them 

 from their innate drowsiness, are like the ostrich which 

 prefers not to see the danger. Neumayr is such a cool and 

 cautious observer, that he allows nothing to pass current 

 but that which is absolutely certain. It is true he holds 

 it to be " extraordinarily probable " that in all forms 

 these gradual transitions have taken place, yet in one 

 case only does he demand unqualified assent, namely, 



