Devonian Ichthyodorulite, Heteracanihus uddeni. 



95 



modified by weathering, and this sometimes renders the rec- 

 ognition of each bed difficult. There is a variable but gen- 

 eral dip to the south and west, and a noticeable diminution 

 in the thickness of the beds to the south. 



Remains of fish are occasionally found in at least four of 

 the beds described above. In No. 2 there is quite a variety 

 of teeth of cestraciont sharks. Many of these teeth resemble 

 the form described as Ptyctodus. From No. 3 a nearly entire 

 armor of a placoid fish was found near Rock Island some 

 years ago. Two small pieces of the plates, or jaws, of these 

 fishes have been found in No. 4, and a fin-spine* has also been 

 taken from this bed. No. 9 contains teeth resembling those 

 in No. 4. The fish remains of Nos. 2-9 may hence be said to 

 resemble those of the Hamilton period in the Eastern States. 



ARTICLE XL— DESCRIPTION OF A DEVONIAN ICH- 

 THYODORULITE, HETERACANTHUS UDDENI, 

 N. SP., FROM BUFFALO, IOWA. 



By Josua Lindahi,, Ph. D. 



The fish-spine referred to by Professor Udden in his paper, 

 "A Brief Description of the Section of the Devonian Rocks 

 in the Vicinity of Rock Island, 111. . . . etc." (Article X of 

 this volume, p. 93), is closely related to the similar spines 

 found in the cement beds of Hamilton Age at Milwaukee, 

 Wisconsin, and described by Professor Newberry under the 

 name of HeteracantJuts politics. As the specimen now under 

 consideration appears to represent a hitherto undescribed 

 species, and necessitates a modification of Professor New- 

 berry's characterization of the genus Heteracanihus, I wish 

 here to give a description of the specimen which Professor 

 Udden has had the kindness to present to the museum of the 

 Cincinnati Society of Natural History. 



* Described hereafter by J. Lindahl under the name Heteracanthus uddeni. — [Ed 1 



3 



