62 UNIVERSITY OF MISSOURI BULLETIN 



Ohio, it would be referred to D. intermedius almost without 

 question. (Plate II, fig. 1). 



The external occipital is comparable in size to D. inter- 

 medius but is quite different in shape. The length of articula- 

 tion with the occipital is 77 mm. and the shape of the articulat- 

 ing edge is different from that of any of the large dinichthyids 

 that have been described. A peculiarity is a shallow elongated 

 depression near the left margin. (Plate II, fig. 2). 



Only a small part of the dorso-median is preserved. Its 

 thickness near the base is 5 cm. and the width of the posterior 

 prong is 3 cm. It is peculiar in having a deep pit on either 

 side of the median line 65 mm. in front of the back margin. 

 These pits have been retouched in the photograph but show 

 no more prominently than in the specimen. The writer knows 

 of no other dinichthyid having the same peculiarity. (Plate 

 II, fig. 4.) 



The bones described above belong to a species about the 

 size of D. intermedius, but each, with the exception of the man- 

 dible, has peculiarities that distinguish it from that species. 

 As noted before it is not known that the bones belong together. 



Formation and locality: Near the top of the Devonian 

 at Louisiana, Mo. Collection of Mr. Rowley. 



Mylostoma eastmani sp. nov. 

 (Plate II, fig. 3) 



Mr. Rowley has collected only one tooth of Mylosto ma 

 It is larger than Mylostoma variablis and differs from that 

 species in shape and structure. The latter is indicated in sur- 

 face markings which are shown in the photograph. The shape 

 is similar to that of the shear teeth of some species of Dinich- 

 thys, but the tooth is of nearly uniform thickness, shows wear 

 all over the figured surface, and the peculiar pores run at right 

 angles to that surface. The greatest length of the element 

 is 9 cm., and the distance from the tip of the slender prong to 

 the opposite side 52 mm. 



Formation and locality: Top of the Devonian at Lou- 

 isiana, Mo. Collection of Mr. Rowley. 



