8 NEW YORK STATE MUSEUM 



The memoir which is now presented, and whose inception is due 

 largely to active interest of the present State Geologist of New York, is 

 intended partially to supply the need of a general conspectus dealing with 

 the fauna of a definite area and within a definite formation It must be 

 understood, however, as being of much more modest pretensions and more 

 limited in scope, than the aforementioned monograph by Professor New- 

 berr)-. As the title indicates, it is concerned chiefly with the Devonic fish 

 fauna of the New York-Pennsylvania region, revised descriptions being 

 offered of every genus and nearly every species entering into its composi- 

 tion. Many of the larger groups have also been redefined in accordance 

 with the present state of our knowledge respecting them. Obviously, how- 

 ever, our understanding of the forms occurring within the boundaries of 

 two political divisions would be incomplete except as they are viewed in 

 relation to other species, genera and faunas, irrespective of their geographi- 

 cal distribution. Moreover, a large proportion of the remains found in one 

 state, owing to inferior preservation or other causes, would be obscure, per- 

 haps even unintelligible, but for the occurrence of identical or kindred 

 species in some other region. Let it be asked, for example, how much 

 would be known of the structure of Bothriolepis if we were unable to 

 extend our acquaintance beyond the extremely fragmentary specimens 

 found in the New York and Penns\ivania Devonic? But as soon as com- 

 parisons are undertaken with the exquisitely preserved Canadian examples, 

 even the poorest fragment from the former region becomes invested with 

 new light and interest. Accordingly, in the following pages, we have not 

 hesitated to take considerable notice, and even to introduce descriptions of 

 extralimital forms, wherever such procedure appeared conducive to a more 

 perfect understanding of the species comprised by the local fauna. And 

 finally, at the end of the systematic descriptions, some general questions are 

 discussed which deal with geographical distribution and with the relations 

 of the fauna as a whole. 



In the matter of formation names, preference has been given through- 



