2o8 KEINHARDT THIESSEN 



Fig. 22. — Part of a thin horizontal section through a layer of attritus 

 largely composed of spore matter, some humic matter, and some carbonaceous 

 matter. The small circular to oval spots represent spore-exines; the irregular 

 black spots, carbonaceous matter. X 150. 



Fig. 23. — Part of a thin cross-section of coal, showing resinous particles 

 in the anthraxylon and in the attritus. 



Fig. 24.— Part of the thin horizontal section of Pittsburgh coal shown in 

 Figure 22, at a very high magnification, showing the spore-exines and other 

 constituents in detail. The spores are characteristic of the Pittsburgh bed. 

 X 1,000. 



Fig. 25.— Part of a thin horizontal section of coal from the Pittsburgh seam, 

 at a very high magnification, showing the pollen grain type of spore-exines, 

 imbedded in a matrix consisting of humic, carbonized, mineral, and earthy 

 matter. X 1,000. 



Fig. 26. — Part of a thin cross-section of anthraxylous coal from the Van- 

 daha mine, Terre Haute, Indiana, showing a large number of oval resinous 

 particles. The original woody issues have decayed in the part shown. X 200. 



PLATE X 



Spore-exines isolated from various coals by means of Schulze's reagent 

 and seen flat-wise. 



Fig, 27. — 'Spore-exine found in the coal from Buxton, Iowa. X 1,000. 



Fig. 28. — Spore-exine predominant in and characteristic of the coal from 

 Buxton, Iowa. X 1,000. 



Fig. 29.— Spore-exine predominant in and characteristic of the Pittsburgh 

 seam. 



Fig. 30. — Exine of a pollen grain, common in all coals. X 1,000. 



Fig. 31. — Spore-exine characteristic of and predominant in the coal from 

 Shelbyville, lUinois. X 1,000. 



Fig. 32. — Spore-exine characteristic of and predominant in the coal from 

 the Sipsey mine, Alabama, Black Creek bed. X 1,000. 



Fig. 33. — Spore-exine from bed No. 6, Illinois coal. X 1,000. 



Fig. 34. — Spore-exines from an Illinois coal, bed No. 6. X 1,000. 



Fig. 35. — Megaspore-exines of a smaller type, found in large numbers in 

 the Shelbyville coal and occasionally in other coals. A megaspore similar to 

 this but with three large air sacks is characteristic of coal from Buxton, Illinois. 



X33- 



Fig. 36. — Seedlike spore-exine from the Illinois coals, bed No. 6. X 100. 



Fig. 37. — Spore-exine found in the coal from bed No. 5, Vandalia, Indiana. 

 X 1,000. 



Fig. 38. — Megaspore-exine predonainant in the coal from Shelbyville, 

 Illinois, but found occasionally in other coals. X 33. 



Fig. 39. — Spore-exines, Spencerite type, common in all coals. X 100. 



