1897.] NEW YORK ACADEMY OF SCIENCES. 283 



Cretaceous, and he was deeply engaged in the preparation of 

 an extended work * on this subject at the time of his final 

 illness. 



The only MS. relating to fossil fishes which was found among 

 his papers by Professor Kemp, his successor in the University, 

 is the one which is now presented. This was probably written 

 between the months of March, 18^0, and June, 1891. The MS. 

 was shown the present editor during the fall of 1892, on his re- 

 turn from abroad, but it was at that time his impression that the 

 paper had been published. His unfortunate error in this regard 

 was discovered only recentl3^ 



The MS. of the present paper proved in essential regards a 

 complete one, as far, at all events, as the letterpress was con- 

 cerned. It required but rearrangement and the insertion of 

 references. The editor's greatest difficulty was encountered 

 on the side of illustrations; the figures of a number of the spe- 

 cies were lacking, and in nearly every case the drawings were 

 detached and unaccompanied by definite labels. In the identifi- 

 cation of these figures the greatest care became, therefore, 

 necessary before the plates could be prepared. In two instances 

 it was found best to omit the species entirely on account of 

 this uncertaint3\ On the other hand two species have been de- 

 fined in spite of the lack of figures, the characters given in the 

 description appearing distinctive. The following figures are 

 from drawings of Miss Mary A. Knight, PI. XXII., figs, 4, 5 ; 

 PI. XXIII., figs. 1, 5-11 ; PI. XXIV., figs. 12, 24-28. It should 

 also be stated that the MS. contained the description of two 

 species of Ptycodus then believed to be new, but now shown 

 definitely, thanks to a fine series of these dental plates in Har- 

 vard Museum, to be but variational forms of P. calceolatus, N. 

 & W. On this account these pa<zes have been omitted. Of 

 PL XXII., figs. 1, 2, 2a, 6 and of PI. XXIIL, 2, 3, 4 are by 

 Mr, Arthur Hollick, The remainder are from photographs by 

 the editor. 



For information in this matter^ as well as for other notes 

 regarding questionable points in the paper, the editor has 

 been greatly indebted to his friend. Dr. C. R. Eastman, of Har- 

 vard University. As far, however, as the personal views of Dr. 

 Newberry were concerned, as for example regarding the sepa- 

 rateness of the genera Dactylodus and Deltodus, the editor has 

 been careful to insert every note that the MS has yielded — be- 

 lieving that the author's long experience with a vast material of 

 these forms has given his views upon these points an especial 

 weight. 



* This monograph has recently been published (Washington, 1897), thanks to the care 

 and labor which its editor, Mr. Arthur Hollick, has devoted to it. 



