GENUS TRILETES 



37 



In contrast, the range of spore body diame- 

 ter on the dry specimens is from 600 to 

 1250 /x (mean 1000 ^ lor 46 specimens). 



The dried specimens compare closely in 

 dimensions with those given by Dijkstra 

 (1955a) for spores of Trilctes brasserti 

 forma 2. His description (Dijkstra, 1955a, 

 p. 334) of the flange of these spores is: 



Appendages of the zone in some (?) rows, 

 strongly anastomosed. Separate shape of the 

 appendages not clearly distinguishable. Border 

 of the zone provided with bar-like processes, 

 50 ijl in length. Periphery of the zone shows 

 some openings, 10-30 fi in diameter. Breadth 

 of zone about 100-500 ll (the mean being 

 290 fx). 



Although he does not mention the aspect 

 of the distal side of the flange, Stach and 

 Zerndt (1931, p. 1123) in their original de- 

 scription of spores of Triletes brasserti de- 

 scribe the flange as follows: 



Die Oberseiten der Aquatorleisten sind uneben, 

 und zwar schwach wellenformig, die Unter- 

 seiten kornig. 



In contrast, Dijkstra (1955a, p. 333) de- 

 scribes the flange development on spores 

 that he designates as Triletes brasserti 

 forma 1: 



Equatorial zone 225-350^ ([rarely] 650 fi) broad, 

 consisting of about eight rows of appendages. 

 Appendages about 12 /x broad, united into 

 groups of 3-5 specimens. Between the append- 

 ages a very thin transparent substance. Ap- 

 pendages towards the periphery ramified with 

 flat leaf-like processes. Between the processes 

 openings 30-60 ^ in diameter. This part of the 

 zone is 150-200^ broad. Arcuate ridges granu- 

 lated, granules 40-50 /j. in diameter (only visi- 

 ble with specimens which have lost their zone). 



This is an excellent typification of the 

 flange on spores of Triletes superbus and, 

 in my opinion, one of the few concrete dis- 

 tinctions between the spores of T. brasserti 

 and T. superbus. Potonie and Kremp 

 (1956) similarly reemphasized the original 

 interpretation rather than accept the 

 broad interpretation of T. brasserti, as ap- 

 plied subsequently to the original descrip- 

 tion by Stach and Zerndt. Dijkstra (1955a) 

 points out that the spores of T. nigrozo- 

 nalis Stach and Zerndt (1931) should be 

 referred to T. brasserti on the basis of a 

 written communication from Zerndt in 

 1941. However, Potonie and Kremp (1956) 

 have described these spores as a species of 



Valvisisporites, to which they referred the 

 auriculate megaspores. 



Dijkstra (1955a, p. 333) pointed out that 

 Triletes rotatus, T. superbus, T. dentatus, 

 and T. brasserti have some features in com- 

 mon and could be confused when one is 

 dealing with poorly preserved specimens, 

 and that in the past various "types" have 

 been united by Zerndt in his distribution 

 charts so that it is impossible to know the 

 exact stratigraphic distribution of these 

 forms as given in the older literature. 

 Potonie and Kremp (1956) state that the 

 spores of T. brasserti are known from the 

 Upper Westphalian B to the Middle West- 

 phalian C in the Ruhr Basin, from the 

 Westphalian B-C in Holland, and from the 

 Westphalian A-C in France. 



In contrast similar spores are known 

 from the Namurian B-C in Poland and 

 Dinantian and Lower Namurian in Scot- 

 land. Cross (1947, p. 287, fig. 2; pi. I, fig. 

 22; pi. Ill, figs. 66-77, 87-90; p. 300-301) 

 reported spores of Triletes brasserti ques- 

 tionably from the Lower War Eagle Coal, 

 and from the Cedar Grove, Chilton, Wini- 

 frede, and Coalburg Coals of the Kanawha 

 Group of the Appalachian Basin. Arnold 

 (1950) reported T. brasserti from the up- 

 per third of the coal of Cycle "E" and the 

 Eaton Sandstone (Cycle "H") at Grand 

 Ledge, and T. subbrasserti from the Eaton 

 Sandstone, the coal of Cycle "D" at Grand 

 Ledge, and the Williamston Coal of 

 Michigan. 



Affinity. — Spores of Triletes brasserti are 

 assumed to be allied with the lycopsids as 

 are those of T. superbus. 



Occurrence. — Spores of Triletes brasserti 

 appear to be restricted to the Tarter, Willis, 

 and Pope Creek Coals in the lower part 

 of the Tradewater Group of Illinois. The 

 species is abundantly represented in the 

 Willis Coal (macerations 625A-B) from 

 Gallatin County, in the Tarter Coal (mac- 

 erations 604A, 901) from Fulton and War- 

 ren Counties, and in the Pope Creek Coal 

 (maceration 602) from Fulton County. 



Sectio Triangulati Schopf, 1938 



Spores in the Triangulati section of Tri- 

 letes are of medium size or smaller. Spore 



