development of the peat swamp (maceration 1958C). 

 These cordaites were adapted to the very wet environ- 

 ments, in contrast to those living on drier, better 

 drained substrate (Phillips et al. 1985). 



In the section of the Lewisport coal studied in de- 

 tail, Botryococcus and Lycospora are most abundant in 

 the coal and overlying black coaly shale. Modern 

 Botryococcus lives in temperate to tropical, fresh and 

 brackish aquatic environments. Lepidophloios and other 

 lycopod trees that produced Lycospora were also 

 adapted to very wet habitats (Phillips and Peppers 

 1984, Phillips et al. 1985, DiMichele and Phillips 1985, 

 DiMichele et al. 1985). Diaphanodendron, Sigillaria, Cha- 

 loneria, and most ferns were adapted to drier or peri- 

 odically drier habitats, where Botryococcus is not likely 

 to thrive. Whether the water was fresh or brackish is not 

 known. 



Other coals in which Botryococcus is common or 

 abundant include the Reynoldsburg, Breckinridge, 

 Mariah Hill, Tarter, Brush, and Delwood. Spores in the 

 sample of the Reynoldsburg Coal that was studied 

 were not sufficiently well preserved to permit making 

 a complete spore analysis. On the basis of spore analy- 

 sis of other samples of the Reynoldsburg Coal (unpub- 

 lished data), we found that Lycospora is most abundant 

 and Densosporites (spores from herbaceous lycopods) is 

 second in abundance. The latter is usually most abun- 

 dant toward the top of coals, which suggests that the 

 peat was still moist but less frequently covered by 

 water during the last stage of peat swamp development 



(Smith 1957, Smith and Butterworth 1967). Spores in 

 maceration 1540 of the Breckinridge coal are also poorly 

 preserved, but the spore assemblage is most similar to 

 what is probably its correlative, the Bell coal bed (un- 

 published data). Lycospora greatly dominates the spore 

 assemblages in the Bell coal and is very abundant in the 

 Mariah Hill and Tarter Coals (fig. 5), which also locally 

 contain abundant Botryococcus. Densosporites and Radu- 

 zonates (from herbaceous lycopods) are well repre- 

 sented in the Mariah Hill Coal (maceration 2205, table 

 2) but are rare in the Tarter Coal (maceration 2066, table 

 2). Maceration 1865 of the Brush Coal contains abun- 

 dant Botryococcus; Lycospora is also abundant, but 

 spores in the maceration are poorly preserved. 



Algae have not been observed in the Pope Creek 

 and Rock Island Coals and equivalent coals in Indiana, 

 which lie between the Tarter and Brush Coals (fig. 3). 

 The Pope Creek and Rock Island Coals contain spore 

 populations that are dominated by fern spores. Ferns 

 were abundant in Pennsylvanian peat swamps that 

 were drier or periodically drier than lycopod-domi- 

 nated swamps (Phillips et al. 1985). Of all the coals in 

 which Botryococcus is well represented, the Lewisport 

 Coal has the most diverse spore assemblages (Peppers, 

 in press), and lycopod spores are not dominant at all 

 sites. Botryococcus has been observed in more samples 

 of the Delwood Coal than in any other coal, and one of 

 the most distinguishing features of its spore assemblages 

 is the overwhelming abundance of Lycospora (table 2). 



PETROGRAPHIC OCCURRENCE OF BOTRYOCOCCUS 



Several coal samples were selected for detailed petro- 

 graphic study using customary petrographic methods. 



Crushed particles representative of the sample 

 were embedded in epoxy and polished to provide sta- 

 tistically representative surfaces for microscopic obser- 

 vations. Vertical illumination microscopy, using an oil 

 immersion lens at 500x magnification, permitted iden- 

 tification of the maceral components that make up the 

 samples. Volumetric percentage of the various compo- 

 nents was determined using point counting procedures 

 on the basis of approximately 500 randomly selected 

 counts. Two types of illumination were used: white 

 light from a 100 W tungsten-quartz-halogen lamp and 

 blue light from a 300 W mercury arc lamp. The latter 

 used a special optical configuration: a heat filter, a BG12 

 excitation filter, a dichroic mirror, and a yellow barrier 

 filter — all of which improved the quality of the resul- 

 tant fluorescence image. This setup significantly im- 

 proved the ability to identify the alginite and other 

 liptinite macerals in the samples. 



Scanning electron microscope (SEM) studies at 

 higher magnifications revealed the ultra-fine structure 

 of the Botryococcus colonies. Millipore filters concen- 

 trated representative residues from the macerations left 

 over from the palynological studies. These residues 

 were dried and coated with a gold-palladium conduc- 



tor under vacuum to enhance the quality of the image 

 in the SEM. 



Botryococcus occurs within a matrix of desmocol- 

 linite, a low reflecting, moderately dark, gray vitrinite 

 (plate 1, A and B). Botryococcus is also mixed with spor- 

 inite in thin beds (plate 1, C and D) and with bituminite 

 in two samples (table 3). 



Bofryococcus-sporinite-rich layers are interbedded 

 with ultra-thin bands of telocollinite, a high-reflecting 

 vitrinite. In addition, scattered inertinite macerals (iner- 

 todetrinite, semifusinite, and more rarely fusinite) oc- 

 cur with Botryococcus. Botryococcus represents 0.5 to 3.2 

 volume percent of the samples studied (table 3). Actu- 

 ally, certain layers of the sample contain much greater 

 abundances of Botryococcus than others, for the algae 

 often occur concentrated within ultra-thin beds of the 

 coal, commonly only 200 um thick. There, they com- 

 posed some 50% to 75% of the ultra-thin coal layer. 

 While these samples are not typical of humic coals, they 

 too are predominately composed of the vitrinite group 

 of macerals (table 3). 



Of particular note is the character of the outer edges 

 of the Botryococcus colonies. These edges appear to re- 

 tain their cuplike structure (plate 1, F), which is made 

 more evident by the SEM examination of macerated 

 samples (fig. 6). The structure of the cups has long been 



16 



