72 UNIVERSITY OF MISSOURI BULLETIN 



evidence is neglected and the entire basis made paleontologic. 

 At no place have arthrodire remains been found in rocks of 

 recognized Mississippian age. It would of course be rash to 

 say that they do not occur above the Devonian, but until 

 they are shown to have passed into the Mississippian they re- 

 main good indices of the Devonian. 



The writer is glad to express his obligations to Mr. R. R. 

 Rowley who kindly allowed his collection to be studied, and 

 to Mr. D. K. Greger and Mr. H. M. Scott who donated speci- 

 mens to the University of Missouri collection. 



EXPLANATION OF PLATES 



Plate I 



Figs. 1, 2, 4, 5, 6. Dinichthys rowleyi sp. nov. 



1. Under side of occipital, about 5-7 natural size. 



2 . Top of dorso-median, about 5-7 natural size. 



4. Top of external occipital, about 5-7 natural size. 



5 . Vomerine tooth, about 2-3 natural size. 



6. Fragment of mandible, about 5-7 natural size. 



All of these bones are from the upper part of the Devonian 

 at Louisiana, Mo. Page 60-61. 

 Fig. 3. Occipital of unidentified Dinichthys. (5-7.) Top of 



the Devonian at Louisiana, Mo. Page 63. 



Plate II 



Figs. 1, 2, 4. Dinichthys missouriensis sp. nov. 



1 . Posterior end of mandible, about 2-3 natural size. 



2. External occipital, about 5-8 natural size. 



4. Much worn dorso-median, about 2-3 natural size. 

 All of these bones are from the upper part of the Devonian 



at Louisiana, Mo. Page 61-62. 



Fig. 3. Mylostoma eastmani sp. nov. Top view of type speci- 

 men, about 5-7 natural size. Top of the Devonian at 

 Louisiana, Mo. Page 62. 



