76 Dr. J. S. Newherry on American Fossil Fishes. 



Of MacropetalichthysitiQiQ are now enumerated four species, viz: 

 M. Manni, Newb. M. Agassizii, v. Myer, sp. 



M. Sullivanti^ Newb. M. rapheidolabis, Owen. 



It is however possible that the last two are identical with the 

 two former^ but just what Owen's species is we shall probably 

 never know, as his description does not tell us and the originad 

 specimen has been lost sight of — neither does von Myer's figure 

 and description furnish the means of making an accurate com- 

 parison with the American fossils. 



Genus Mach^racanthus, Newb. 



Spines often of large size, flattened, curved, ancipital, un«ym- 

 metrical, dextral and sinistral; edges and point generally acute; 

 base somewhat narrowed, with a rough and irregular extremity; 

 central cavity large, — reaching nearly to the apex ; external sur- 

 face covered with a thin coating of enamel, in some species 

 smooth, in others punctate or longitudinally striated; micro- 

 scopic structure that of dense ivory -like bone. 



One of the smaller species of this genus is that described by 

 Prof Hopkins in the Proc. of the American Association, vol. 

 viii, p. 287^ represented by the accompanying wood cut, taken 

 from that volume. 



