62 



ILLINOIS STATE GEOLOGICAL SURVEY 



Affinity. — These prepollen grains are 

 pteridospermic and probably largely co- 

 extensive with the Medullosaceae (Schopf, 

 Wilson, and Bentall, 1944) . Some may lack 

 distal grooves, as do those of Codonotheca 

 (Schopf, 1948) , but all seem to be charac- 

 terized by a medially deflected suture. 



Occurrence. — According to Dijkstra 

 (1955a), this prepollen is found in the 

 Westphalian and Stephanian of European 

 coal basins. 



MONOLETES Spp. 

 Plate 14, figures 1-10 



Discussion. — Very few specimens of 

 Monoletes were noted to lack the distal 

 longitudinal folds as are typically shown 

 by figures 6 and 9 on plate 14. Many speci- 

 mens (pi. 14, fig. 8) from the "West Frank- 

 lin" Coal exhibit long thin folds of the 

 coat, but these generally are variously dis- 

 posed relative to the long axis. All ex- 

 amples observed have a medially deflected 

 suture and some appear to possess a third 

 ray (pi. 14, figs. 5, 7, 9) . The third ray 

 shown by figure 5 on plate 10 is 26^ in 

 length. One of the smallest prepollen, and 

 also one of the oldest specimens, is 200 ^ 

 in length (pi. 14, fig. 1) ; one of the more 

 robust specimens is more than 500 ^ in 

 length (pi. 14, fig. 6) . 



In a few prepollen grains of many differ- 

 ent samples of coal, the inner membrane is 

 observed to be pulled away from the outer 

 coat (pi. 14, figs. 1, 3, 4, 7) . In any one 

 prepollen mass where most specimens ap- 

 pear "normal," one or two may have 

 "shrunken" inner membranes. The speci- 

 men illustrated by figure 7 on plate 14 is 

 similar to those originally described as 

 Monoletes aureolus by Schopf (1938). Al- 

 though the inner body of this specimen is 

 very dark — the negative of this illustration 

 required extensive dodging in order to 

 show central detail — the inner coat is only 

 6 ^ thick, a few microns thicker than the 

 inner coat of the holotype of M. aureolus. 

 The outer coat, poorly preserved, appears 

 very thin, but is actually about 20 /x thick 

 around the margin. The holotype of M. 

 aureolus also appears to have an outer coat 



of similar thickness. Although the pre- 

 pollen may represent a distinct species of 

 Monoletes, it also is possible that it repre- 

 sents "sports" of prepollen which, if nor- 

 mally developed, might be referred to M. 

 ovatus. Such "sports" of Spencerisporites 

 also possess much smaller and darker cen- 

 tral bodies than do the majority of spores 

 of Spencerisporites. 



Monoletes prepollen often occurs in 

 masses, as that shown in figure 10 on plate 

 14, from the "Divide" Coal in which Mono- 

 letes is abundantly represented. The pre- 

 pollen is very glossy under reflected light. 



Occurrence. — Monoletes is not repre- 

 sented in upper Mississippian coals. No 

 prepollen was observed in the coals of the 

 Black Creek, Mary Lee, or Pratt Groups 

 from the Warrior Basin of Alabama, al- 

 though resin rodlets, of medullosan origin 

 and in many instances associated with 

 Monoletes prepollen, were present in some 

 of the coal beds of the Black Creek and 

 Mary Lee Groups. 



Monoletes is commonly represented in 

 two coals (macerations 795, 910) and 

 sparsely represented in other coals of the 

 Caseyville Group. The prepollen is first 

 abundant in the Babylon Coal (maceration 

 588) . It is also abundant in one sample of 

 the Rock Island (No. 1) Coal (maceration 

 528B) and in two Tradewater coals (mac- 

 eration 950, 95 IB) from Goose Lake, 

 Illinois. 



Monoletes prepollen is generally present 

 to common in most coals of the Tradewater 

 Group and may be abundant in the Col- 

 chester (No. 2) , No. 5, Briar Hill (No. 

 5a) , and Herrin (No. 6) Coals of the Car- 

 bondale Group. In the McLeansboro 

 Group, prepollen is common in the Indiana 

 VII (?) Coal (maceration 939A) and the 

 "West Franklin" Coal (maceration 831) ; 

 abundant in the Friendsville Coal (macera- 

 tions 153, 135, and 490D) , the "Divide" 

 Coal (maceration 811); present in the 

 "LaSalle" Coal (maceration 600) , the "Bo- 

 gota" Coal (maceration 133), and the 

 "Woodbury" Coal (maceration 703) ; rare 

 in the Friendsville (?) Coal (maceration 

 136) . Monoletes is also known from the 



