56 NEW YORK STATE MUSEtlM 



Thence it spread northeastward into Russia, westward into the Eifel 

 District, and northwestward into the Hudson and James Bay region. 

 From this latter region we may suppose it to have passed south- 

 ward through Ontario by means of a passageway connecting with 

 the Appalachian gulf over the area that is now occupied by Ohio 

 and Indiana, where the fauna reached its climacteric. The most 

 conspicuous elements of the fauna are Arthrodires and Ptyctodonts, 

 groups which began immediately upon their introduction to attain 

 a most remarkable development. Throughout the Hamilton and 

 later Devonic, conditions must have been eminently favorable in the 

 Appalachian sea for the further specialization of armor-clad Dip- 

 noans of the type represented by Dinichthys and its congeners. Like 

 their earliest predecessors, they became of greatest importance 

 locally in Ohio. 



The wide interest to all concerned with the philosophy of paleon- 

 tology and the far-reaching significance of such detailed investiga- 

 tions as are brought together here, are very effectively set forth in 

 the following paragraphs. 



There are no other means for attaching significance to a truth 

 except by perceiving its relations to other truths. Thus far we have 

 been concerned principally in assembling, and to some slight extent 

 in correlating recognizable truths; in a word, facts of observation 

 have been brought into orderly array. The next step is to examine 

 them in their bearing upon other known facts, to deduce their gen- 

 eral significance, and to assign to the results a commensurate worth 

 in surveying the whole field of paleontological inquiry. The ulti- 

 mate yield of scientific study is the fruition of philosophical ideas. 



To obtain a large perspective of the body of facts at our disposal, 

 it is desirable to marshal them in different ways, and to examine 

 them from different points of view. Their relevancy from a 

 geological standpoint needs consideration, with the object of draw- 

 ing from them conclusions of geological import. In still larger 

 measure it behooves us to consider them as an increment to zoologi- 

 cal science, compacting its substantial framework and vastly extend- 

 ing our knowledge of the evolutionary history of organisms. Are 

 we proposing to ourselves an explanation of life, our vision must 

 include not only living matter as we find it today, but also those 

 manifestations of it that existed in the remote past. Side by side 

 with the development of the individual we must examine the evolu- 

 tionary history of the race. The more we learn of vital processes 

 now operating, the better able are we to understand their operation 

 in times anterior to our own. Comparisons that are enlightening 

 when made between members of the modern fauna may often be 

 profitably extended so as to include members of extinct faunas. 

 Where the time element acts as an impediment to our studies it 

 must be eliminated so far as possible. Zoology of the past does not 

 differ in essence from zoology of the present, any more than ancient 

 history differs fundamentally from modern. 



