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 Palzontologists, 
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 dees he demand unqualified assent, namely, 
