14 THE COAL MEASURES AMPHIBIA OF NORTH AMERICA. 



Of 100,000 nodules, 20,000 will be barren or contain only indeterminate fragments ; 

 68,500 will contain plants; 7,500 will contain insects, Crustacea, myriapods, scor- 

 pions, spiders, and other arthropods; 3, goo will contain fish coprolites or scales; 95 

 may contain fish or fragments of fish; 4 may contain mollusks; and I may contain 

 an amphibian or a fragment of one. 



Perhaps even 100,000 is low as a basis of estimate. Mr. Carr was of the opinion 

 that I nodule in every 500,000 might contain an amphibian. 



The beds from which the nodules are usually collected occur along both banks 

 and in the bottom of the creek, in two localities. One locality known as the Bartlett 

 place is situated 8 miles southeast of Morris, in Grundy County, Illinois, Wauponsee 

 Township, N.W. quarter, section 30, Township 33, Range 8, the land being now 

 owned by Mrs. Emma Akerly, of Wilmington, Illinois. 



The fossil-bearing nodules occur throughout 6 to 8 feet of shale along both banks 

 of the creek at the "upper beds" (plate i.fig. 3), as the Bartlett place is called. They 

 may also be seen in the bed of the creek, when the water is low (plate I, fig. 4), 

 still embedded in the shale. With a potato fork the shale is easily turned and the 

 nodules come out like potatoes. One sometimes finds a "pocket" of nodules from 

 which as many as a peck may be secured. Nearly every nodule has a fossil at the 

 "upper beds," but all of the fossils are not well preserved, possibly only i or 2 out 

 of every 10 being worth carrying to the museum. The nodules crack best when wet, 

 and it requires some skill to crack them evenly. They seem quite light and, in 

 one place where the stream curves, are piled in a long windrow. On this were found, 

 in nodules cracked by the frost, several good crustaceans and many good plants. 



TABLE OF PENNSYLVANIC FORMATIONS. 



c Northern Appalachian. Bituminous. 



Pennsylvania-Ohio. Illinois. 



Monongahela nr Upper Productive Coal Measures . -JBreak 1 '' /?< "'* ) ' 



Conemaugh or Lower Barren Ames limestone near middle: 



(*) (Pitcairn) Coal No. 6. 



Allegheny or Lower Coal Measures 



Freeport 



(*) (Cannelton) Coal No. 2 (*). 



Kittanning (*). (Morris?) (Mazon Creek). 

 (Linton). 



Clarion. 



Home wood. 



Mercer. 



Conoquenessing. 



Sharon. 



(*) marks the position of the Amphibian-producing horizons in these regions. (After Schuchert.) 



The fossils at the "upper beds" are localized into special strata. At one place 

 in the upper part of the deposit, in a reddish shale, one finds that insects are more 

 abundant than they are lower down. The Crustacea seem to come from appar- 

 ently the same shale. At the lower end of the deposit certain definite species of 

 Pecopteris are localized. It is an interesting fact that one seldom finds a Neurop- 

 teris at the "upper beds." The most abundant fossils are the various species of 

 Pecopteris and Annularia. When specimens of Neuropteris are found they are 

 usually discovered at the lower end of the exposures. In one place behind the 

 "island" very blue nodules, hard and flinty and with sometimes well-preserved 



