No. 514] 



DIXIC III 'ID II) AIIMOR PLATE 



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That the ventral armor of the present specimen be- 

 longed to a primitive type is shown: (1) by the fad thai 

 the antero-ventromediaii ami postcro -vent roinedian are 

 not fused as in such specialized forms as D. terrHlr and 

 (2) by the fact that the anterior lateral angles of the 

 antero-ventrolaterals are directed posteriori} giving this 

 portion of the ventral shield an outline similar to that ol 

 Coccosteus (see Fig. 3). 



The fact that the antero- and postero-ventromedians are 

 united by suture and not merely touching or even sepa- 

 rate shows an advance from the condition of these ele- 

 ments in Coccosteus, but taking the sum of the char- 

 acters in the ventral shield we have, on the whole, a 

 closer approximation to this latter genus than to 

 Dinichthys. 



In his recent memoir s Dr. Kastman lists eight species 

 of Dinichthys as occurring in the Devonian of the New 

 York-Pennsylvania Province. Of these >ix are confined 

 to the upper Devonian, that is, they are found only above 

 the top of the Hamilton shales. Of these, three at least 

 are common to both the New York-Pennsylvania and the 

 Ohio province, while three appear to be restricted to the 

 New York-Pennsylvania province. The Middle Devonian 

 yields but two definite species, D. lincolni Claypole and 

 D. halmodens (Clarke). Both are, as far as known, 



