coalif ied, and its morphology has not been significantly 

 altered. 



Under the microscope, the polished cross-sectional 

 surfaces of these colonies apparently show many open 

 cups. Along the outer edges of the colonies in the fluo- 

 rescence images (produced under blue-light illumina- 

 tion; plate 1, F), one can focus into the colonies to a 

 depth of approximately 10 to 20 um, which helps con- 

 firm the cups (which appear as tubules) are still open. 



In the fluorescence images, the darkened, thumb- 

 nail-shaped areas along the colony edges indicate par- 

 tially or wholly open cups. Under the microscope, a 

 flattened cup would not display these shadings. 



SEM observation of many Botryococcus colonies ap- 

 pears to show a high abundance of open cups (fig. 6). 

 The cups seen in SEM observations, however, might 

 have been opened by the maceration process used to 

 prepare the specimens. That process, using Schulze's 

 solution (an oxidizing mixture of a saturated solution 

 of KCIO3 and HNO3) followed by a 5% solution of 

 KOH, might have caused the once closed or flattened 

 cups to open. The evidence from the fluorescence pol- 

 ished surfaces, however, suggests more conclusively 

 that the cups were not completely closed by the coalifi- 

 cation process. 



CONCLUSIONS 



Botryococcus, a boghead alga, was observed at a total of 

 43 sites in the Reynoldsburg, Breckinridge, Bell, St. 

 Meinrad, Mariah Hill, Dunbar, Tarter, Lower Block, 

 Hermon, Brush, Lewisport, Buffaloville, Delwood, 

 Bancroft, and New Burnside Coals and in an unnamed 

 coal in Indiana equivalent to the Murphysboro Coal. 

 Some of these coals are correlative (fig. 3). The alga was 

 found most frequently (14 sites) in the Delwood Coal 

 and the Lewisport and Buffaloville Coals (6 sites), 

 which are equivalent. No pattern is apparent in the 

 location or abundance of Botryococcus in various coal 

 beds. The alga ranges from rare to abundant, and spore 

 assemblages are poorly preserved in some macerations 

 in which it is abundant. 



Spore analysis of the Lewisport coal and overlying 

 and underlying strata at a site in Union County, Ken- 

 tucky, indicates that Botryococcus is most abundant in 

 the coal and overlying coaly shale in which Lycospora, 

 produced by Lepidophloios and other lycopod trees, is 

 most abundant (fig. 4). Botryococcus is least abundant in 

 the underclay and overlying gray shale in which Grana- 

 sporites medius, whose affinity is with Diaphorodendron 

 and Synchysidendron, and fern spores are most abun- 

 dant. Sphenopsid spores are most abundant where 

 Botryococcus is rare. 



Botryococcus is most abundant in other coal beds in 

 which Lycospora is abundant. Since Botryococcus flour- 

 ished in standing fresh to brackish water, this associa- 

 tion is additional evidence that lycopod trees were 

 adapted to very wet environments that were peri- 

 odically flooded. 



The information on the paleoecology of coal- 

 swamp floras provided by this study helps interpret the 

 formation and depositional environments of the coals. 

 Since Botryococcus is an indicator of fresh to brackish 



water (i.e., indicates nonmarine environments), its 

 presence in significant amounts may indicate the loca- 

 tion of low-sulfur coal because nonmarine shale com- 

 monly directly overlies low-sulfur coal. 



In the Illinois Basin, Botryococcus has been observed 

 in coal from the Reynoldsburg Coal Bed to an unnamed 

 coal in Indiana correlative with the Murphysboro Coal 

 Member and ranging in age from the end of the Mor- 

 rowan to the begining of the Desmoinesian (fig. 3). 

 Although Botryococcus existed from at least as early as 

 the Ordovician to the present, the alga has not been 

 observed in any of the hundreds of macerations of coals 

 above the Murphysboro Coal, including the Springfield 

 (No. 5) and Herrin (No. 6) Coal Members, which extend 

 for thousands of square miles and are major economi- 

 cally important coals. The great abundance of Lycospora 

 in the Herrin and several other coals above the Mur- 

 physboro Coal indicates abundant available water in 

 the peat swamps. The absence of Botryococcus above the 

 Murphysboro Coal in the Illinois Basin is presently 

 difficult to explain. Because the alga occurs only be- 

 tween the Murphysboro and Reynoldsburg Coals, its 

 presence can be used in a general way to identify the 

 lower part of the Tradewater Formation in the Illinois 

 Basin. 



Botryococcus occurs in coal mostly as irregular colo- 

 nies and is concentrated in ultra-thin layers, where 

 along with sporinite and minor amounts of other mac- 

 erals it is embedded in desmocollinite vitrinite. While 

 the associated macerals and lithologic character of the 

 coal beds indicate the coals are bituminous in rank, the 

 Botryococcus colonies were not coalified or significantly 

 changed in form. In fact, microscopic observation sug- 

 gests that the algal cups have not undergone perma- 

 nent collapse during the entire period of coalification. 



18 



