204 Agassiz 1 Contributions to the 



developement of other animals of a later period were to be es- 

 tablished. They appear now, like a prophecy in those earlier 

 times, of an order of things not possible with the earlier com- 

 binations then prevailing in the animal kingdom, but exhibiting 

 in a later period, in a striking manner, the antecedent considera- 

 tion of every step in the gradation of animals. 



This is, however, by no means the only, nor even the most re- 

 markable case, of such prophetic connections between facts of 

 different dates. 



Recent investigations in Palaeontology have led to the discovery 

 of relations between animals of past ages and those now living, 

 which were not even suspected by the founders of that science. 

 It has, for instance, been noticed, that certain types which are 

 frequently prominent among the representatives of past ages, 

 combine in their structure, peculiarities which at later periods 

 are only observed separately ia different, distinct types. Sauriod 

 "Fishes before Reptiles, Pterodactyles before Birds, Ichthyosauri 

 before Dolphins, etc. 



There are entire families, among the representatives of older 

 periods, of nearly every class of animals, which, in the state of 

 their perfect development exemplify such prophetic relations, and 

 afford, within the limits of the animal kingdom, at least, the 

 most unexpected evidence, that the plan of the whole creation 

 had been maturely considered long before it was executed. Such 

 types. I have for some time past, been in the habit of calling 

 prophetic types. The Sauroid Fishes of the past geological ages, 

 are an example of this kind. These Fishes, which have preceded 

 the appearance of Reptiles, present a combination of ichthyic 

 and reptilian characters, not to be found in the true members of 

 this class, which form its bulk at present. The Pterodactyles 

 which have preceded the class of Birds, and the Ichthyosauri 

 which have preceded the appearance of the Cetacea,* are other 

 examples of such prophetic types. These cases suffice for the 

 present, to show that there is a real difference between embryonic 

 types and prophetic types. Embryonic types are in a measure 

 also prophetic types, but they exemplify only the pecularities of 

 development of the hio-her representatives of their own types ; 



*In the text the author is made to say Crustacea instead of Cetacea; 

 and we observe other typographical errors, which the publisher should 

 endeavour to avoid in succeeding volumes. 



