64 UNIVERSITY OF MISSOURI BULLETIN 



One specimen of this species, collected by Mr. D. K. Gre- 

 ger three feet from the top of the Craghead Creek shales of 

 Callaway County, Missouri, is in the University collection. 

 The specimen is less than half as long as the type but seems to 

 belong to the same species. It will be noted by referring to 

 figure 3 of plate IV of this paper and Eastman's figures in the 

 American Naturalist and the Iowa report that the tooth under 

 discussion seems to be much broader in the middle but it is 

 possible that part of Eastman's specimen is missing. East- 

 man does not describe the tritoral part of the upper tooth. 

 In the present specimen it extends nearly the entire length, is 

 narrow, and the parallel rows of punctations, so conspicuous 

 in P. calceolus, occur only at the hinder part. The tritor is 

 34 mm. long, 8 mm. wide at the base at one end and narrowing 

 to 2.5 mm. at the other. At the top it is 5 mm. wide at the 

 hinder end and thins to a point at the front end. 



Ptyctodus calceolus Newb. and Worthen 

 (Plate III, figs. 3, 4) 



Ptyctodus calceolus is by far the most abundant form oc- 

 curring in the Missouri Devonian. Mr. Rowley has more 

 than two hundred teeth in his collection and the writer collected 

 eight fair tritors and six or seven poor ones in about an hour's 

 work on the formation near Louisiana. The writer has col- 

 lected a number of these teeth from a Kinderhookian sandstone 

 just below the Chouteau near Providence, Missouri, and from 

 the same sandstone near Fulton, Missouri, and numerous local- 

 ities in Montgomery and Warren Counties, Missouri. The 

 Phelps sandstone of southwestern Missouri contains them in 

 abundance. In another paragraph a brief note on the stratig- 

 raphy of the Devonian of Missouri is given and it is stated 

 as the opinion of the writer that the teeth were derived from 

 the erosion of the Devonian shales that contained them. The 

 teeth found at Louisiana are often in good condition and show 

 little wear, but those found at Providence and elsewhere in the 

 Kinderhookian sandstone are greatly worn, rarely more than 

 half a tooth being found. While collecting at Louisiana, the 



