68 UNIVERSITY OF MISSOURI BULLETIN 



Eoorodus typus gen. et. sp. nov. 

 (Plate IV, figs. 22-24) 



Type one tooth with part of one end missing. The in- 

 complete tooth is two centimeters long. The length from the 

 middle to the end of the perfect part is 14.5 mm. The greatest 

 width is 12 mm. at the middle of the tooth from where it tapers 

 gradually to a width of 5 mm. and thence abruptly to a sharp 

 point. The greatest height of the crown, 11.5 mm., is at the 

 summit of the median cone which occupies the entire width 

 of the tooth and more than half of the length. The cone is 

 low and smooth save for a few crenulations around the base. 

 The top of the tooth outside the cone has many small irregular 

 crenulations that run from the edge toward the middle. The 

 surface of the tooth is not punctate. The root is missing and 

 was probably cartilaginous. 



The form was probably ancestral to Orodus. Surface 

 ornamentation of the Orodus type is developing and a median 

 cone, similar to the one in that form but larger in proportion 

 to the rest of the tooth, is present. 



Formation and locality: Top of the Devonian shales at 

 Louisiana, Mo. Collection of Mr. Rowley. 



Psephodus sp. undet. 



(Plate IV, fig. 18) 



One imperfect tooth from the Devonian at Louisiana seems 

 to belong to this genus, though it has not crenulated margins. 

 In shape it is similar to Psephodus obliquus of St. John and 

 Worthen from the Kinderhook of Iowa. The writer photo- 

 graphed and studied the tooth but has not been able to compare 

 it directly with other Psephodus teeth, as the owner did not 

 care to have it taken from Louisiana. 



Collection of Mr. Rowley. 



