374 PALAEONTOLOGY OF ILLINOIS. 



was ever given by Agassiz of the spine which he named Ph. sulteres, so that it 

 is not certain that it should be considered generically identical with the one 

 now under consideration, but there can be no question that our spine belongs 

 to the same genus with McCoy's Ph. arcuatus, and as he has framed a generic 

 description on that, our species may be almost considered a type. The great 

 size of our specimen, however, requires a qualification of so much of McCoy's 

 description as refers to the size ("Pin spine of small or moderate size "). 



Formation and locality : Burlington limestone ; Quincy, 111. 



Note on the Genus Rinodus, N. and W. 



When the descriptions of the fish remains described in Vol. II, were writ- 

 ten, we had not access to all of Pander's Monographs of the Fossil Fishes of 

 Russia, Since then we have obtained them, and find in his paper (Uler die 

 Ctenodiptfirinen des Devonischens Systems, pp. 48-51, PL viii and ix,) descrip- 

 tions and copious illustrations of a group of fish teeth from the Devonian rocks 

 of Russia, which include two species unmistakably generically identical with 

 that peculiar one described by us (Vol II, p. 106, PI. x, figs. 10, lOa, lOb), un- 

 der the name of Rinodus calceolus. These are grouped by Pander in the genus 

 Ptyctodus, forming his two species, Pt. obliquas and Pt. ancinnatus. Both these 

 species are ornamented on the sides, where ours is plain, and hence are appar- 

 ently specifically distinct; but, in the generality of form and structure, the re- 

 semblance is so close that no one would hesitate to include them all in one genus. 

 Our species, Rinodus calceolus, must therefore, take the name of Ptyctodm 

 calceolus. 



So far as we can learn, no teeth of this kind have been found elsewhere in 

 Europe than in Russia, and there only in the Devonian strata. It is, there- 

 fore, a fact of peculiar geological interest that a very closely allied species 

 should reappear in far distant America, in the same geological horizon. 



