III. SOME NEW AND LITTLE KNOWN FOSSIL 

 VERTEBRATES. 



By J. B. Hatcher. 



(Plates I-IV. ) 



The present paper is based upon material brought together by the 

 paleontological expedition of 1900, for which Mr. Andrew Carnegie 

 generously supplied the necessary funds. The material has been freed 

 from the matrix and prepared for study, either directly by, or under 

 the immediate supervision of, Mr. A. S. Coggeshall, the chief prep- 

 arator of the Museum in the Section of Vertebrate Paleontology. 

 In the performance of this work Mr. Coggeshall has shown unusual 

 skill and patience. The illustrations are from drawings by Mr. W. J. 

 Carpenter and photographs by Mr. A. S. Coggeshall. In each in- 

 stance they accurately illustrate important details of form and structure 

 in the specimens described. 



Class PISCES. 

 Platacodon nanus ^ Marsh. 

 In a former paper I have called attention to the undoubted ichthyic 

 nature of the diminutive teeth collected by the writer several years 

 ago and described by the late Professor Marsh as mammalian under 

 the above name.' Subsequent to Professor Marsh's description of the 

 types of this genus and species the present writer discovered in the 

 same immediate locality, from which he secured the type specimens, 

 two small dental plates, each bearing ankylosed teeth of the same size 

 and pattern as the detached teeth described by Professor Marsh. The 

 nature of these dental plates and the teeth they supported fixed at the 

 same time their ichthyic nature and their identity with Platacodon. 

 Both of these ])oints Professor Marsh fully realized and frequently ex- 

 pressed in conversation with the writer. Other pressing duties doubt- 

 less prevented his making the necessary correction prior to his un- 

 timely death. During the past season I had occasion to visit the same 



1 See Am. Journ. Sci., Vol. XXXVIII, Aug., 1899, p. 178. 

 2 See Science, N. S., Vol. XII, Nov. 9, 1900, p. 719. 



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