GENUS TRILETES 



43 



ent in the "Makanda" Coal (maceration 

 142) in Illinois and in the Battery Rock 

 Coal (maceration 733) in Kentucky. A few 

 specimens occur with those of T. cf. T. 

 hirsutus in the Pope Creek Coal (mac- 

 erations 916, 917) and Rock Island (No. 1) 

 Coal (maceration 929) . 



Abundant spores, typical of Triletes glo- 

 bosus, seem to be characteristic of the upper 

 coals of the Caseyville in Illinois. 



Triletes globosus Arnold var. (A) 

 Plate 4, figures 1-3 



Description. — Megaspores trilete, gener- 

 ally compressed proximo-distally, ranging 

 in diameter from 330 to 630 n (mean 515 ^ 

 for 48 specimens) , with the polar axis — 

 not including the apical prominence — 

 slightly shorter than the equatorial diame- 

 ter. Length of trilete rays generally a little 

 less than three-fourths the spore body ra- 

 dius; lips up to 26 n in height near base of 

 flaplike apical expansion. Lips increasing 

 rather abruptly in height to 80 to 130 ^ at 

 apex (pi. 4, fig. 1), forming an apical 

 prominence up to 100 ^ in width. Contact 

 areas commonly smooth, sometimes orna- 

 mented with indistinct, minute, sharply 

 pointed spines up to 4 ^ in length. 



Distal surfaces covered with closely 

 spaced spines 10 to 20 ^ in length and 5 to 

 10/x in width (pi. 4, fig. 2); spines fused 

 into a solid flange up to 30 ^ in width at 

 the arcuate ridges. Spines short and ir- 

 regularly connected to one another near 

 their bases or by spans extending from 

 rather bulbose nodes on the spines above 

 the level of the spore coat (pi. 4, fig. 3) . 

 Spines terminating in fine sharp points ex- 

 tending from the bulbose nodes. Spore 

 coat 10 to 15 /a thick, reddish brown by 

 transmitted light. 



Discussion. — The ornamentation on these 

 spores, especially characteristic of mega- 

 spores of lower Mississippian age, is pres- 

 ent on the Triletes globosus-type mega- 

 spores in upper Mississippian and lower- 

 most Pennsylvanian rocks. Because the 

 ornament gives an irregularly reticulate ap- 

 pearance to the spore coat, I refer to this 



genera] type of ornamentation as "catenu- 

 late ornamentation." 



Spores of Triletes globosus var. (A) may 

 be comparable with those designated origi- 

 nally as T. tenuispinosus var. brevispinosa, 

 type 13a, variety I by Zerndt (1937a), in 

 general form, length of rays, and height of 

 apical prominence. However, they lack the 

 tuberose nodules and characteristic con- 

 spicuous contact area folds described by 

 Zerndt as radiating from the apex. The 

 spore, mounted dry and photographed by 

 reflected light (pi. 4, fig. 1), shows only 

 vaguely defined radiating contact area 

 folds; this specimen shows the maximum 

 development of such folds noted on these 

 Hardinsburg megaspores. Zerndt (1937a), 

 in his descriptions, did not mention the 

 presence of a narrow flange or connecting 

 spans joining the spines. According to 

 Dijkstra (1952b) forma I (variety I of 

 Zerndt and T. tenuispinosa var. brevi- 

 spinosa Zerndt in Schopf, Wilson, and 

 Bentall, 1944) of Zerndt's varietal form of 

 the species is represented in the Namurian 

 A and B of Turkey, whereas forma II 

 (variety II of Zerndt and T. tenuispinosa 

 var. secundus in Schopf, Wilson, and Bent- 

 all) of Zerndt's varietal form is represented 

 in the Namurian C. In addition, Dijkstra 

 (1957) noted that forma I occurred in 

 every coal that he studied from the Lime- 

 stone Coal Group of Scotland. 



Compared to the spores described by 

 Horst (1955) as Setosisporites hirsutus var. 

 brevispinosa (Zerndt) Potonie and Kremp, 

 those of the coal in the Hardinsburg For- 

 mation are smaller. Horst stated that this 

 variety is characteristic of the Rand Group, 

 but those typical of the species occur in 

 younger beds. He noted the sporadic oc- 

 currence of the varietal form in the Na- 

 murian A, B, and B or C, and in the West- 

 phalian A, B, and C. 



The spores of Triletes globosus var. (A) 

 may be comparable, except for the less con- 

 spicuous development of contact area 

 ridges with those described by Bennie and 

 Kidston (1886, p. 108) as Triletes IV from 

 the Calciferous Sandstone Series in Scot- 

 land. Triletes IV is described thus: "Macro- 

 spore very small [570-510 /x ], outer surface 



