No. 494] ZOOLOGICAL PROGRESS 



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which are to be found some of most specialized and pro- 

 digious land and water animals known. No possible con- 

 sideration of the recent orders of reptiles would ever lead 

 one to suspect the remarkable nature of these ancient 

 forms, and the so-called affinities of the recent orders 

 become meaningless in the light of the true ancestral 

 relations as seen in the past history of the group as a 

 whole. Tempting as the field of speculative phylogeny is, 

 its results can never be of much value till they receive the 

 endorsement of actual history as traced in fossil ancestry. 

 In this connection I can not do better than quote a short 

 passage from Huxley, who, as you well know, was an 

 ardent student of fossil as well as living animals. In his 

 essay on "The Advance of Science" he says: 



A classification which shall represent the process of ancestral 

 evolution is, in fact, the end which the labors of the philosophical 

 taxonornist must keep in view. But it is an end which cannot be 

 attained until the progress of paleontology has given us far more 

 insight than we yet possess into the historical facts of the case. 



It is plain that the history of the animal kingdom is to 

 be sought for not through ingenious speculations on the 

 recent groups of animals, but by the persistent and patient 

 exploration of the fossil-bearing rocks. 



Although the study of animal genealogy, as outlined by 

 fossil remains, is a relatively novel field, it has already 

 yielded certain general results worthy of careful atten- 

 tion. It is customary at present to group all species of 

 animals under some ten or twelve main divisions or phyla 

 of the animal kingdom. These phyla have doubtless been 

 evolved from some common group of animals in the 

 remote past, and consequently, in tracing back their his- 

 tory as represented by fossil forms, it is not unreasonable 

 to expect that their lines would gradually converge toward 

 this common ancestral stock. In some instances, like the 

 flat-worms, the phylum is known only through its modern 

 representatives, and these representatives are of such 

 consistency that it is not surprising that none of these 

 animals have been preserved in the fossil state. But, 



