IS PALEONTOLOGY OP ILLINOIS. 



Fins large; dorsal triangular, about as high as broad at base, 

 composed Of about 2G rays; ventrals lower, but containing near 

 the same number of rays; pectorals oblong, rounded at extrem- 

 ity, composed of about 10 rays; anal fin extending from ventrals 

 to caudal, containing 40 or more rays; caudal as broad as anal, 

 and apparently composed of an equal number of rays. 



This pretty fish would seem to have been an inhabitant of many of the lagoons 

 in the coal marshes, in different parts of what is now the valley of the Missis- 

 sippi, as I have specimens of it from several localities in Ohio, Indiana and 

 Illinois. It is probable, also, that it will prove to be one of the species which 

 have been found in the rocks, associated with the "Albert" coal, in New 

 Brunswick. I have some imperfect specimens from there of a species very 

 closely allied to this, in which the only difference observable is the coarser and 

 stronger ornamentation of the scales. All the species from the Albert mine, 

 figured by Dr. Jackson, are unmistakably Palseonesci, remarkable for the elab- 

 orate ornamentation of the head, bones and scales, and for the large dorsal 

 scales, which, in common with the species before us, are borne by all of them. 

 The finest specimens of P. peltigerus which I have are from beds of cannel coal 

 in different localities, forming one of the many facts cited by the writer (Am. 

 Jour, of Science, March, 1857) to sustain his conclusion that cannel coal was 

 formed from a carbonaceous pulp, derived from thoroughly macerated vegetables 

 suspended and deposited in water. 



Formation and locality: Coal Measures, Fulton county, Illinois. 



Genus RHIZODUS, Owen. 



Gen. Char. — Jaws large, massive and bony, bearing several 

 large, compressed, double-edged teeth,. with sulcated bases in 

 each dental bone, with numerous intermediate ones of similar 

 form; scales large (1 to 5 inches in diameter), rotundate-quadrate 

 in outline, thin, inner surface marked by concentric wavy lines 

 of growth, and very finely reticulated; often marked with a 

 tubercle of attachment; exposed portion of exterior surface cov- 

 ered with a fine vermicular tuberculation. 



The considerations which actuated McCoy, in separating the large, thin, 

 nearly plain scales, found in the Coal Measures, from the more massive and 



