GEXUS TRILETES 



45 



Pennsylvanian coals from the Wabash 

 County diamond drill cores (macerations 

 798, 797, 796) . They also have been found 

 in the Battery Rock Coal (maceration 587) 

 in Illinois, in the French Lick (maceration 

 151) and Pinnick (maceration 150) Coals 

 and in the shale (maceration 163) above 

 the Pinnick Coal from Orange County, In- 

 diana. They also are probably present in 

 the Jefferson (rare) , Middle Ream, Jag- 

 ger, and Pratt Coals of the Warrior Basin 

 in Alabama. These spores occur rarely with 

 spores typical of T. globosus in the Reyn- 

 oldsburg Coal (maceration 618). 



The general occurrence of Triletes glo- 

 bosus var. (B) is therefore in the lower 

 part of the Caseyville Group in Illinois. 



Triletes globosus Arnold var. (C) 

 Plate 4, figures 11, 12 



Description. — Megaspores trilete, having 

 no preferred compressional orientation, 

 probably originally oblate spheroidal, rang- 

 ing in diameter from 480 to 770 ^ (mean 

 675 fx for 20 specimens) , polar axis — not 

 including apical prominence — generally 5 

 to 10 percent less than equatorial dimen- 

 sion. Apical prominence from 115 to 165 ^ 

 in height and up to twice as wide (pi. 4, 

 fig. 11) . Length of trilete rays about three- 

 fifths the spore radius. Diameter of contact 

 areas from one-half to three-fourths that of 

 the proximal surface. Arcuate ridges gen- 

 erally developed, about 20 ^ in width and 

 15 fx in height. Contact areas generally 

 smooth, in some specimens covered with 

 tubercles similar to, but smaller than, those 

 on the distal surface. 



Distal surface covered with tubercles (pi. 

 4, fig. 12), generally flattened-hemispheri- 

 cal, rarely with pointed tips, up to 5 to 26 /x 

 in length and 5 to 52 ^ in diameter on any 

 one spore. Some specimens have large tu- 

 bercles interspersed among smaller tuber- 

 cles. 



Spore coat 26 to 42 ^ thick, deep reddish 

 brown by transmitted light. 



Discussion. — These spores are very simi- 

 lar in body form and development of apical 

 prominence to those of Triletes cf. T. hir- 

 sutus and T. globosus, although the mean 



diameter is larger than the maximum di- 

 ameter found on spores of either species in 



this investigation. The apical prominence 

 of spores of T. globosus var. (C) is a No 

 generally higher and wider. The greatest 

 distinction is the tuberose distal ornamen- 

 tation on spores of T. globosus var. (C) as 

 opposed to spinose ornamentation. Their 

 slightly larger body size, generally 1. 

 tubercle size, and thicker spore coat dis- 

 tinguish them from the spores originally 

 described by Zerndt (1937a) as T. tenu'i- 

 spinosusvai. brevispinosa variety I. In addi- 

 tion they do not have radiating folds on 

 the contact area. Their body form and api- 

 cal development, however, indicate a close 

 relationship with spores of the T. globosus- 

 type. 



Occurrence. — These megaspores are ap- 

 parently restricted to the Willis Coal, being 

 common in the upper part of the Willis 

 Coal (maceration 625A) and present in the 

 Willis (?) Coal (maceration 631) , Gallatin 

 County, Illinois. 



Triletes cf. T. hirsutus (Loose) 



Schopf, Wilson, and Bentall, 1944 



Plate 5, figure 7 



Discussion. — Some megaspores, noted in 

 Tradewater coals, bear longer, more deeply 

 notched spines than those that occur on 

 spores typical of Triletes globosus. The few 

 measured specimens range from 565 to 

 635 [x in diameter and possess an apical 

 prominence up to 65 /x in height. The spore 

 coat ranges from 15 to 35 ^ thick. The con- 

 tact areas are generally covered with tiny 

 spines up to 7 p. in length and 5 ^ in diame- 

 ter. Distal spines are 37 to 87 fx long, bifur- 

 cate or more deeply notched than spines on 

 T. globosus. Although these spores, of all 

 the T. globosus-type spores, appear most 

 similar to those of T. hirsutus, none has 

 spines as long as 200 fx (reported by Wicher 

 [1934a] and Dijkstra [1955a]) or is as 

 ramose as those illustrated by Potonie and 

 Kremp (1955, pi. 4, figs. 29a, 29b). 



Occurrence. — These spores were found 

 in the Tarter (maceration 914) and Pope 

 Creek (macerations 916, 917) Coals, Mer- 

 cer County, and were found in abundance 



