EASTMAN : CARBONIFEROUS FISHES FROM THE CENTRAL WEST. 195 



III. SPECIES OF FOSSIL FISHES FROM THE 

 MISSISSIPPIAN SERIES. 



Under this head descriptions are given of several new species from the 

 Kinderhook and Keokuk limestones of the Mississippi Valley, and the struc- 

 ture and systematic relations of certain others are considered concerning which 

 a difference of opinion amongst authors has existed. For an opportunity to 

 examine some of the type specimens described in the Palaeontology of Illinois 

 the writer is indebted to the courtesy of Prof. C. W. Rolfe, of the State Uni- 

 versity at Urbana, and to Mr. C H. Crantz, Curator of the State Museum at 

 Springfield, Illinois. 



The following table shows the commonly accepted subdivisions of the Mis- 

 sissippian series for this region : — 



SECTION OF THE LOWER CARBONIFEROUS. 



r 



Mississippian 

 Series. 



Chester limestone and shales (including 

 Genevieve Group or ) the " Kaskaskia limestone "). 

 ^^''■g^- St. Louis limestone. 



Warsaw limestone (in part). 



Augusta (Osage) Group f Keokuk limestone. 



or Stage. I Burlington limestone. 



Kinderhook Group or 



Hannibal shales 



r Chouteau limestone. 



Stage. \ "'*""*""' y;'^'-- 



I Louisiana limestone. 



ELASMOBRANCHII. 



PLEURACANTHIDAE. 



PHOBBODUS St. John and Worthen. 



Of this genus three species are represented in the Devonian of this country, 

 two in the Mississippian series, and one in the Permo-Carboniferous, including 

 those described in the present paper. It is probable, however, that at least 

 two forms ascribed by Newberry and Worthen to the " genus " Diplodus, 

 namely, D. incurvus and D. duplicatus, should be referred to Phoebodus 

 as commonly understood. 



