14 PALAEONTOLOGY OF ILLINOIS. 



ginous, and in consequence of the hardness of the rock, well 

 preserved specimens are more difficult to obtain from this bed 

 than from those below. Very fine specimens are occasionally 

 obtained from the soft shales in which the limestone are im- 

 bedded, and are found weathered out upon the sloping hill-sides 

 below the outcrop of the bed in which they were originally 

 inclosed. 



In the Coal Measures the remains of fishes are comparatively 

 rare in Illinois, and a single specimen will perhaps be the average 

 reward of the collector for his day's labor in this horizon. The 

 shales above the Belleville coal in St. Clair county, the argilla- 

 ceous limestone and shale forming the roof of the coal seam 

 near Springfield, and the State House quarries on Sugar creek, 

 in Sangamon county, and an equivalent limestone at La Salle, 

 have afforded nearly all the specimens yet found in the upper 

 Carboniferous beds in Illinois. 



The new species presented at this time comprise all that 

 have been collected during the prosecution of the Geological 

 Survey of the State up to 1862, as well as the private collection 

 of one of the authors (A. H. W.), the result of more than ten 

 years' labor, while a resident of Warsaw, in Hancock county, 

 and in close proximity to some of the richest deposits of ichthyic 

 fossils yet discovered on this continent. Although the new 

 species now presented to the scientific world far exceed in 

 number all that have hitherto been found in the paleozoic rocks 

 of North America, we nevertheless believe that the localities 

 mentioned are by no means exhausted, but will yet afford very 

 many other new types. 



The following query may have been suggested to 'the inquir- 

 ing mind by the phenomena we have thus briefly attempted to 

 describe : Why should the remains of fishes be found in such 

 profusion, in the limited horizons which we have termed fish 

 beds, while they are comparatively rare in the intervening- 

 strata? , It seems to have been the probable result of one of 



