GENUS MONOLETES 



61 



796, 797, 908) . They also are present to 

 rare in the following Tradewater coals: 

 Babylon (maceration 588) , Tarter (macer- 

 ation 901), Rock Island (No. 1) (macera- 

 tion 929), Bald Hill (maceration 520A) 

 and an unnamed coal above DeKoven 



(maceration 35) . In the Carbondale Group 

 they are generally present in the Colchester 



(No. 2) Coal (macerations 611, 579C, 

 603B-C, 826, 582), in the Summum (No. 4) 

 Coal (maceration 463) , and in the Grape 

 Creek (No. 6) Coal (maceration 878) . 

 Spores of this species are rare in the Indi- 

 ana IV (maceration 881) and Springfield 



(No. 5) (maceration 630) Coals, but seem to 

 be common in the Briar Hill (No. 5a) 

 Coal (maceration 633A) . In the McLeans- 

 boro Group they are present in the Indiana 

 VII (?) Coal (maceration 939A) , the "Bo- 

 gota" (maceration 133), and "Woodbury" 



(maceration 703) Coals; common in the 

 Friendsville Coal (maceration 490D) ; 

 abundant in the "LaSalle" (maceration 

 600) and Friendsville (?) (maceration 

 136) Coals. 



Calamospora sp. 

 Plate 13, figure 12 



This spore is 185^ in diameter, much 

 smaller than the spores of Calamospora cf. 

 C. laevigata with which it occurs. The 

 spore coat is extremely thick in relation to 

 spore size, especially at the contact area. 

 This single example w r as found in the "La- 

 Salle" Coal (maceration 600) of the 

 McLeansboro Group. 



Genus Monoletes (Ibrahim) Schopf, 

 Wilson, and Bentall, 1944 



Type species. — Monoletes ovatus Schopf, by desig- 

 nation of Schopf, Wilson, and Bentall, 1944. 



Description. — Prepollen of Monoletes 

 appear bilateral and monolete although 

 they are asymmetrically bilateral in that 

 the suture deviates from a straight line and 

 exhibits a characteristic angular deflection 

 medially. Occasionally what may be a short 

 vestigial ray is observed at the point of de- 

 flection. Schopf, Wilson, and Bentall 

 (1944) noted that the prepollen may have 



originated in tetrahedral tetrads. Com- 

 pressed specimens are nearly circular to 

 rounded lenticular in outline, ranging 

 from slightly more than 100 ^ to more than 

 500 p in length. The distal surface on ex- 

 panded prepollen is often marked by two 

 longitudinal grooves separated by a well 

 rounded umbo. Compressed examples usu- 

 ally have longitudinal folds parallel to the 

 distal grooves. The coat is minutely granu- 

 lose, up to 18/x thick proximally and dis- 

 tally, sometimes less than 5 ^ thick at the 

 base of the distal grooves. An inner mem- 

 brane is frequently present. More complete 

 discussions of the morphology of Monoletes 

 prepollen were given by Schopf (1938) , 

 Schopf, Wilson, and Bentall (1944), and 

 Schopf (1948). 



Discussion. — Schopf, Wilson, and Ben- 

 tall (1944) pointed out that the two recog- 

 nized species, Monoletes ovatus Schopf and 

 M. ellipsoides (Ibrahim) Schopf, are wide- 

 ly distributed and must still be regarded as 

 rather generalized types. Prepollen of these 

 two species were distinguished by Schopl 

 (1938) on the basis of published descrip- 

 tions and illustrations available at that 

 time which indicated that M. ellipsoides 

 lacked distal grooves. It now appears, with 

 the illustration of the type of M. ellipsoides 

 by Potonie and Kremp (1956, pi. 22, fig. 

 478) that these spores also possess distal 

 grooves. It would seem that morphological 

 features of prepollen of the two species 

 overlap to a considerable degree. 



Potonie and Kremp (1956) recognized 

 Monoletes aureolus Schopf as a species of 

 Schopfipollenites, a synonym of Monoletes, 

 but Schopf, Wilson, and Bentall (1944) 

 referred this species to Zonalo-sporites 

 Ibrahim. This prepollen is similar to that 

 of Monoletes but appears to have a thin 

 outer coat and thick inner coat. 



The specimens illustrated on plate 14, 

 figures 1 to 9, show some of the natural, 

 compressional, and preservational varia- 

 tions in aspect of isolated, compressed 

 Monoletes prepollen. At present there is 

 no advantage to referring these to either of 

 the two widely cited species, although some 

 could readily be referred to M. ovatus 

 Schopf. 



