56 



ILLINOIS STATE GEOLOGICAL SURVEY 



the morphological changes and intergrada- 

 tions between spores of the two species with 

 the passage of time. Although only 52 

 measured specimens are reported below, 

 many more observations and spot-check 

 measurements were made during the 

 course of this study. 



Dijkstra (1955b, p. 7) stated that Cross 



(1947) reported Triletes radiatus (Ibra- 

 him) Schopf, Wilson, and Bentall in coals 

 of the Appalachian Basin. From Cross' 



(1947, p. 301) description it is more likely 

 that Cross was referring to T. radiatus as 

 described by Zerndt (1937a) (T. radiosus 

 Schopf, Wilson, and Bentall) and not to 

 T. radiatus (Ibrahim) Schopf, Wilson, and 

 Bentall. Cross (1947, fig. 2, p. 287) did, 

 however, report the occurrence of Cirratri- 

 radites gracilis in the Cedar Grove, Chilton, 

 Winifrede, and Coalburg Coals from the 

 upper part of the Kanawha Group (Potts- 

 ville Series) and from the No. 5 Block Coal 

 from the lower part of the Allegheny Series. 

 Schopf (1949) noted, in his discussion of 

 bladdered spores of this type, the occur- 

 rence of spores similar to those of C. (?) 

 gracilis Schopf, Wilson, and Bentall in 

 some upper Pennsylvanian coals in Illinois. 

 He also questioned Dijkstra's (1946) sug- 

 gestion that this species and Ibrahim's 

 Sporonites radiatus are closely related. 



Although seemingly most abundant in 

 older coals of the Caseyville Group of Illi- 

 nois, some spores of Spencerisporites occur 

 sporadically in coals of the Tradewater, 

 Carbondale, and McLeansboro Groups. 

 Those younger coals in which Spenceri- 

 sporites is fairly commonly represented are 

 the Willis Coal, DeKoven Coal, No. 5 Coal, 

 and a few of the coals in the McLeansboro 

 Group. No spores of Spencerisporites were 

 noted in the Warrior Basin coals examined 

 or in coals of upper Mississippian age. 



Spencerisporites radiatus (Ibrahim) 

 n. comb. 



1932 Sporonites radiatus Ibrahim, in Potonie, 

 Ibrahim, and Loose, p. 449; pi. 16, fig. 25. 



1933 Zonal es-sporites radiatus (Ibrahim) Ibrahim, 

 p. 28-29; pi. 3, fig. 25. 



1934 Triletes karczewskii Zerndt, p. 27; pi. XXXI, 

 fig. 3. 



1944 Triletes radiatus (Ibrahim) Schopf, Wilson, 



and Bentall, p. 24. 

 1944 Endosporites (?) karczewskii (Zerndt) Schopf, 



Wilson, and Bentall, p. 45-46. 

 1946 Microsporites karczewskii (Zerndt) Dijkstra, 



p. 64, pi. 4, fig. 40. 

 1951 Spencerisporites karczewskii (Zerndt) Chalo- 



ner, p. 862; figs. 1, 2, 6, 7. 

 1955 Endosporites (?) radiatus (Ibrahim) Dijkstra 



(1955a), p. 314-316, 342-343; pi. XLV, fig. 54. 



1955 Microsporites radiatus (Ibrahim) Potonie 

 and Kremp, in Horst, p. 192-194; pi. 18, fig. 

 15; pi. 19, fig. 16. 



1956 Microsporites radiatus (Ibrahim) Dijkstra, 

 in Potonie and Kremp, p. 157-158; pi. 20, figs. 

 449, 450. 



Spencerisporites cf. S. radiatus (Ibrahim) 

 Plate 13, figures 1-6 



Description. — Spores trilete, commonly 

 in proximo-distal compressions, character- 

 ized by a more or less circular body cavity 

 (in proximal view) which is encircled 

 equatorially by an inflated bladder (pi. 13, 

 fig. 2) . Bladder triangular to subtriangular 

 in proximo-distal outline, more or less disk- 

 shaped transversely, widest at opposite ends 

 of trilete rays, and possessing a marginal 

 flange. Total diameter of spores, including 

 bladder and marginal flange, from 272 to 

 412 fx (mean 354^ for 27 specimens) . On 

 any one spore, one diameter, taken from 

 corner to opposite midpoint of interradial 

 margin, seemingly longer than the other 

 two diameters. Marginal flange from less 

 than 15 to 40 ^ wide at corners of bladder 

 and less than 10 to 29 /x wide interradially. 

 Total flange width, measured on both sides 

 of specimen, averaging 10.5 percent of the 

 total spore diameter. On several specimens, 

 upper and lower surfaces of bladder at 

 equatorial attachment area appear to be 

 30 ii apart at the juncture of the trilete 

 rays and bladder, but only 15 /x apart at the 

 interradial margin. 



Trilete rays generally prominent. Lips 

 thin, membranous, sometimes split apart 

 (pi. 13, fig. 1), straight to sinuous, up to 

 36 /jl in height, sometimes expressed as thin 

 folds extending from the inner bladder 

 margin to outer margin of flange (pi. 13, 

 figs. 4, 5a) . Each contact area invariably 

 ornamented w r ith distinct, fine, sometimes 

 broken lines or striations radiating gener- 



