GENUS TRILETES 



39 



containing abundant triangulate spores, 

 except that the Rock Island (No. 1) Coal, 

 in particular, seems to have a large pre- 

 ponderance of spores with fine-meshed dis- 

 tal reticulation. 



The size range given in the description 

 above exceeds that given by most previously 

 published descriptions. Most specimens are 

 less than 900 ^ in over-all diameter. The 

 largest specimen observed, from the Indi- 

 ana VII (?) Coal (maceration 939A) . has 

 a flange 267 /* wide at one radial extremity. 

 This specimen is not comparable to those 

 of Triletes laxomarginalis Zerndt (as de- 

 scribed by Bhardwaj, 1955) , but has all the 

 characteristic features of T. triangularis . 



Although many of these spores have 

 papillate inner membranes, the ornamenta- 

 tion does not seem to be present on all ex- 

 ternally ornamented spores or on all de- 

 nuded spores. Perisporal ornamentation ef- 

 fectively masks the internal ornamentation. 



Affinity. — The affinity of these spores is 

 with the herbaceous lycopods, as discussed 

 under the section Triangulati. 



Previously Recorded Occurrences. — Dijk- 

 stra (1955a) noted that these spores occur 

 in the Carboniferous of all coal basins 

 studied so far, but that they are perhaps 

 less abundant in the Stephanian. Guennel's 

 (1954, fig. 3) chart, approximating the 

 vertical and geographic distribution of this 

 species, emphasized the lack of megaspore 

 studies done in this country. 



Occurrence. — No triangulate spores were 

 observed in upper Mississippian coals or in 

 the coals of the Black Creek, Mary Lee, and 

 Pratt Groups of the Warrior Basin in Ala- 

 bama. Although spores of this species are 

 fairly common in the oldest Caseyville age 

 coal in a Wabash County, Illinois, diamond 

 drill core (maceration 798) , they are rare 

 to absent in other coals of the Caseyville 

 Group. 



In the Tradewater Group triangulate 

 spores are abundant to common in some 

 samples of the Babylon (maceration 588) , 

 Willis (maceration 625A-B) , Pope Creek 

 (maceration 602) , Murphysboro (macera- 

 tion 550), Wiley (maceration 525A-B), 

 Davis (maceration 518A-B), and DeKoven 



(maceration 519A) Coals, and in an un- 

 named coal above the DeKoven Coal. 



Although represented in most coals of 

 the Carbondale Group, spores of this spe- 

 cies are most abundant in the Summum 

 (No. 4) Coal (maceration 463) and com- 

 mon in the Colchester (No. 2) Coal (mac- 

 eration 603B-C) and in the Herrin (No. 6) 

 Coal (Schopf, 1938). In the McLeansboro 

 Group these spores are common in the In- 

 diana VII (?) Coal (maceration 939A) , 

 present in the Friendsville (maceration 

 135) and "Bogota" (maceration 133) 

 Coals, rare in the Friendsville (?) (macera- 

 tion 136) and in the Friendsville (macera- 

 tion 490-D) Coals. This species is also 

 known from the Danville (No. 7) Coal. 



Although the species has a long strati- 

 graphic range in the Illinois coal basin, it 

 is best represented in coals of the Trade- 

 water and Carbondale Groups. 



Sectio Incertus 



Megaspores of Triletes hirsutus (Loose) 

 Schopf, Wilson, and Bentall, and T. hir- 

 sutus var. brevispinosa Zerndt, and those of 

 T. praetextus Zerndt were referred to the 

 sections Aphanozonati and Zonales, respec- 

 tively, by Dijkstra (1946) . Schopf, Wilson, 

 and Bentall (1944) had referred T. hir- 

 sutus questionably to the section Lageni- 

 cula. Because they believed Triletes to be 

 an illegitimate generic designation and 

 because the above megaspores did not seem 

 to be allied with Lepidodendraceae, as are 

 the typically lageniculate spores, Potonie 

 and Kremp (1954) accepted and amended 

 the generic designation Setosisporites of 

 Setosisporites hirsutus (Loose) Ibrahim. 

 In 1955 Potonie and Kremp also referred 

 T. praetextus Zerndt and T. globosus Ar- 

 nold to Setosisporites. 



Potonie (1954a, 1954b) stated that the 

 megaspores of Setosisporites have been 

 found in cones allied with the Bothroden- 

 draceae. These megaspores are distinct 

 from those typical of the Lepidodendraceae 

 in that the conspicuous apical prominence 

 rises, not from the ends of the rays as in 

 most typical lageniculate spores, but near 

 the apex of the spores. Thus the area of the 

 contact surfaces is much greater than that 



