DEVONIAN FISHES OF IOWA 193 



In the detailed and in most respects very accurate description 

 of the holotype given by the original author, it is stated that 

 the dentition presents "an aspect highly similar" to that of 

 Dinichthys, and comparisons are instituted between it and D. 

 herzeri, which also has the functional margin of upper and lower 

 plates denticulated. This resemblance of jaw-parts is of suf- 

 ficient weight, in our opinion, to justify the transfer of the 

 species from Coccosteus, where it was doubtfully placed by Dr. 

 Clarke, to Dinichthys. Of special significance from a taxonomic 

 standpoint are the vomerine teeth, which are described as fol- 

 lows by the same author: "Each is concave on the inner surface, 

 convex externally, and bore a somewhat extended apophysis [or 

 process], which in each case has been broken off. There is no 

 evidence of denticles or a tuberculated surface; the lower edge 

 is, however, rather sharp and would have served a cutting pur- 

 pose. " 



Formation and locality. Marcellus Division (Erian) ; New 

 York State. 



Dinichthys lincolni Claypole. 

 (Plate II, Fig. 20) 



1893. Dinichthys lincolni E. W. Claypole, Amer. Geol. 12, p. 177, text-fig. 



1906. Dinichthys lincolni L. Hussakof, Mem. Amer. Mus. Nat. Hist. 9, p. 



117, 142. 



1907. Dinichthys lincolni C. R. Eastman, Mem. N. Y. State Mus. 10, p. 129, 



pi. 7, figs. 4-6. 



Known only by a single right vomerine tooth of about the size 

 of the corresponding element in D. intermedins Newberry, and 

 very similar to it in general form. The external surface, how- 

 ever, not only along the symphysial margin, but also over nearly 

 all of the exposed portion, is covered with enlarged conical tuber- 

 cles, or even denticles, which are arranged in more or less regular 

 vertical series. The externo-lateral process which serves for the 

 attachment of the tooth to the preorbital, is well developed, 

 but distally somewhat compressed. 



The unique tooth upon which this species is founded possesses 

 a number of interesting features. In the first place, as already 

 noted by Claypole, it is singular in having the entire outer face 



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