154: ON THE METHOD OF ZADIG. 



trusted, if employed with due caution, to lead to a just 

 interpretation of fossil remains ; or, in other words, we 

 may look for the verification of the retrospective prophe- 

 cies which are based upon them. 



And if this be the case, the late advances which have 

 been made in palseontological discovery open out a new 

 field for such prophecies. For it has been ascertained 

 with respect to many groups of animals, that, as we trace 

 them back in time, their ancestors gradually cease to ex- 

 hibit those special modifications which at present charac- 

 terise the type, and more nearly embody the general plan 

 of the group to which they belong. 



Thus, in the well-known case of the horse, the toes 

 which are suppressed in the living horse are found to be 

 more and more complete in the older members of the 

 group, until, at the bottom of the Tertiary series of 

 America, we find an equine animal which has four toes 

 in front and three behind. No remains of the horse 

 tribe are at present known from any Mesozoic deposit. 

 Yet who can doubt that, whenever a sufficiently exten- 

 sive series of lacustrine and fluviatile beds of that age 

 becomes known, the lineage which has been traced thus 

 far will be continued by equine quadrupeds with an in- 

 creasing number of digits, until the horse type merges in 

 the five-toed form towards which these gradations point? 



But the argument which holds good for the horse, 

 holds good, not only for all mammals, but for the whole 

 animal world. And as the study of the pedigrees, or 

 lines of evolution, to which, at present, we have access, 



