I 78 NEW YORK STATE MUSEUM 



ZOOLOGICAL CONCLUSIONS 



In the short space remaining at our disposal we can not dwell further 

 upon these broader, more general topics, and may as well confine ourselves 

 to a brief review of the more obvious zoological and geological considera- 

 tions resulting from a study of Devonic fishes. Those desirous of consult- 

 ing a full account of the introduction and succession of the class Fishes, as 

 revealed by the paleontological record, will find this subject adequately 

 treated in the third volume of Zittel's Handbook of Palaeontology^ and in 

 Smith Woodward's admirable compendium, Outlines of Vertebrate Palaeon- 

 tology. Other useful works of a more popular character are Dean's Fishes, 

 Living and Fossil, and Jordan's recent comprehensive treatise, A Guide to 

 the Study of Fishes, in two well illustrated volumes. An article aiming to 

 give a recapitulation of the essential facts of paleichthyology is contained 

 in the Annual Report of the New Jersey Geological Survey for 1904, and 

 another dealing with the general principles of piscine evolution, is the presi- 

 dential address of Dr A. S. Woodward,' printed in the Proceedings of the 

 Geologists' Association for 1906. 



The last mentioned paper is remarkable for its breadth of treatment of 

 several burning problems in the study of fossil fishes, as it is now pursued, 

 attention being called particularly to the following : 



1 The nature and order of the successive advances in anatomical struc- 

 ture which have suddenly infused new life into the class — the "expression 

 points" as Cope termed them. 



2 The new possibilities of development which arose with each successive 

 "expression point." 



3 The direction of the various abortive lines of advance and degene- 

 ration in each successively higher grade. 



The results of such an investigation have obviously the same far- 

 reaching significance as those derived from a study of evolutionary series 

 of Cephalopods, to cite only one group of invertebrates that has been pro- 



^The Study of Fossil Fishes. Proc. Geol. Ass'n. 1906. 19: 266-82. An abstract of 

 this address is given in Nature 1906. 74: 597-99. 



