Devonian Ichthyodorulite, Heteracanthus uddeni. 



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The bottoms of all the furrows in our specimen are even — 

 not "sinuous," or "denticulate," as Newberry describes the 

 "sutures" of H. politus — while the outlines of their borders 

 are determined by the form of the lateral edges of the adja- 

 cent ridges. Thus both, or one, or neither of the borders 

 may be sinuous. In our specimen (see Fig. 6) only two 

 ridges of the anterior side have regularly denticulated edges 

 (with about twenty teeth to the half-inch); consequently the 

 furrow which separates them has both borders sinuous, while 

 the furrow next in order on either side has its anterior border 

 sinuous, the posterior even ; all the following furrows of the 

 lateral faces have both borders even. There occur, however, 

 particularly on the inner (right) side of the specimen, occa- 

 sional minor irregularities in the edges of some ridges in 

 various portions of the shaft, somewhat reminding of the 

 undulating lines in Newberry's figure 4a, though very differ- 

 ent from the denticulations of the two anterior ridges. 



The proportion of length to greatest width is about 3 to 1 

 (length, 5.9 inches; width, 2 inches). In this our specimen 

 differs greatly from Newberry's description of H. politus, 

 where the proportion is about 6 to 1 (length, 8 to 10 inches; 

 width, i 1 /, inches). 



These different proportions, and the above-described den- 

 ticulations of the anterior ridges, characterize our specimen 

 as the type of a new species, for which I propose the name 

 Heteracanthus uddeni, in honor of the discoverer, my 

 esteemed friend, Prof. J. A. Udden. 



If Mr. Miller's reason for changing the name of the 

 genus — viz, that the name Heteracanthus was pre-occupied 

 for a genus of worms — be regarded valid, the name would 

 stand as Gamphacanthus udde?ii. 



Formation and locality : Devonian, Hamilton Group; bed 

 No. 4 (Udden 1. c); crinoidal limestone; near Buffalo, Iowa. 

 Found by Prof. J. A. Udden, of Augustana College, Rock 

 Island, Ills. 



The type specimen is the property of the Cincinnati Society 

 of Natural History, and is entered in the Museum Catalogue 

 as No. 14,558. 



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