GENUS TRILETES 



33 



anastomose towards their extremities to 

 form a rimlike border. The outer edge of 

 the rim is commonly ornamented with non- 

 uniformly spaced thorn-shaped spines (pi. 

 8, fig. 1) rather than with fingerlike projec- 

 tions. On the basis of the rim ornamenta- 

 tion, the spores may be referable to T. ro- 

 tatus var. denticalata Zerndt. 



However, those spores found in the shale 

 above the Pinnick Coal possessed fingerlike 

 projections on the margin of the rim and 

 are very similar, in the straplike appear- 

 ance of the radiating processes, to those il- 

 lustrated by Zerndt (1937a) and by Horst 

 (1955) . The straplike processes are appar- 

 ently not as fully developed on the spores 

 originally described by Bartlett. Bartlett's 

 spores, like those described above, lack the 

 distal ornamentation of, are smaller than, 

 and possess a less copious appendage 

 growth than the spores of Triletes ramosus. 

 Bartlett's specimens were macerated from 

 coal pebbles, of assumed early Pennsylva- 

 nian age, found in the glacial drift of 

 Michigan. 



Although it is assumed that the spores of 

 Triletes rotatus and those of T. ramosus 

 are allied with the lycopsids, the spores 

 have not yet been found in cones. 



Known occurrences of spores of Triletes 

 rotatus are in the Dinantian and Namurian 

 A and B in some European coal basins (Po- 

 tonie and Kremp, 1956). Dijkstra (1952b) 

 noted their occurrence in the Namurian C 

 of Turkey and in the Westphalian B of the 

 Belgian Campine. Dijkstra (1957) also re- 

 ported their common occurrence in the 

 Limestone Coal Group (Namurian) of 

 Scotland. 



Occurrence. — Spores of Triletes rotatus 

 are abundant in a Caseyville age coal (mac- 

 eration 910) sampled in a gob pile of an 

 abandoned mine in a fault block zone, 

 Pope County, Illinois. A few specimens 

 were noted in the shale (maceration 163) 

 above the Pinnick Coal of Indiana. They 

 also are present in a thin coal (maceration 

 455) in deposits of possible early Pennsyl- 

 vanian age found in a sinkhole deposit at 

 Lincoln Quarry, Will County, Illinois. 



Triletes ramosus Arnold, 1950 

 Plate 8, figures 3-6; text figure 3 



1950 Triletes ramosus Arnold, p. 72-74; pi. Ill, fig. 



2; pi. IV, figs. 1, 2; pi. V, figs. 1-3. 

 1956 Rotatisporites ramosus (Arnold) Potonie 



and Kremp, p. 134-135. 



Description. — Spores trilete, typically 

 compressed proximo-distally or obliquely, 

 characterized by an encircling flange of 

 flattened cylindriform appendages. Spore 

 body round to subtriangular, 705 to 1150^ 

 in diameter (mean 975 /x for 36 specimens, 

 more than half of which are greater than 

 1000 fj) . Trilete rays prominent, lips 

 straight to sinuous, generally more than 

 100 [x in height at apex, up to 234 ^ on one 

 specimen. 



Contact surfaces generally smooth, some- 

 times ornamented with small tubercles (pi. 

 8, fig. 3a) . Fairly closely spaced appendages 

 arising from the spore body slightly proxi- 

 mal to the geometrical equator, extending 

 outward from juncture with spore body as 

 much as 575 ^ (pi. 8, figs. 4a, 5) , and fusing 

 and anastomosing near their extremities 

 to form a rimlike border from which 

 fingerlike processes, up to 52 ^ in length, 

 project (pi. 8, figs. 4b, 6) . Appendages be- 

 coming shorter toward the distal pole, but 

 generally present over the entire distal sur- 

 face (pi. 8, fig. 3b) ; the shorter distal ap- 

 pendages generally discrete and club- 

 shaped, in some specimens branching or 

 adjacent appendages joined. 



Spore coat ranging from 23 to 52 fx in 

 thickness and, in one specimen, enclosing 

 a folded inner membrane. Spore body dark 

 reddish brown, appendages yellow by trans- 

 mitted light; spore body dull brown, ap- 

 pendages and upper margin of lips glossy 

 dark brown to amber by reflected light. 



Discussion. — Some spores of this species 

 were measured both wet and dry. Text fig- 

 ure 3 illustrates the amount of shrinkage 

 observed, averaging about 19 percent. All 

 the measurements given above were made 

 on wet specimens or on those mounted in 

 balsam. Spore coat thickness is variable, 

 even on an individual spore; the spore coat 

 on one spore ranged from 26 to 52 p and 

 was thinnest in the area of the contact 

 surfaces. 



