FRUCTIFICATIONS FROM THE MAZON CREEK FLORA 11 



Spores probably belonging to the same species as those of S.. latiloba 

 have been recorded (Peppers, in progress) from several coals in the Mattoon 

 Formation in the Illinois Basin. These are of special interest because of con- 

 siderable variation in the development of a reticulate sculpture. Except for the 

 larger size (37 to 61 ym) of Apiculatasporites casperatus Merendez and Azcuy, 

 1969, this species compares rather closely with spores of Stellatheca latiloba . 

 Doubinger and Rauscher (1966) described and illustrated a species, Foveospo rites 

 insculptus Playford var. minor , which compares rather closely with the punctate or 

 reticulate forms from Stellatheca latiloba . They also described a species identi- 

 fied as Apiculatisporis (?) globosus Butterworth and Williams, 1958, which shows 

 similarities to the non-reticulate spores of S. latiloba. However, specimens of 

 Apiculatisporis globosus illustrated by Butterworth and Williams appear to have 

 larger and more widely spaced cones than those of Doubinger and Rauscher. The 

 spores described by Doubinger and Rauscher, however, come from strata of Vis^an 

 age and are considerably older than the Mazon Creek flora. 



Since the ornamentation of the spores from our fructification might be con- 

 sidered granulose by some workers, an attempt was made to compare these spores with 

 species of Cyclogranisporites . Of these spores, CL. leopoldi (Kremp) Potonie and 

 Kremp, 1955, is probably the most similar to the spores of Stellatheca latiloba. 

 Potonie' and Kremp (1955) noted that the grana of C_. leopoldi are mostly rounded 

 on the ends or weakly conical, but no mention was made of fusion of the ornaments. 

 Spores that Smith and Butterworth (1967) assigned to Cyclogranisporites cf. minutus 

 Bharadwaj, 1957, are also somewhat like the spores of Stellatheca latiloba. 



The size and variation in fusion of sculptural elements in the spores of 

 Stellatheca are similar to those found in spores of Botryopteris from coal balls by 

 Phillips and Rosso (1970). 



Genus MYRIOTHECA Zeiller, 1883 

 Synonym: Polytheca H. Potonie\ 1900 



Mvriotheca is an easily identifiable genus, which bears free, ovoid, ses- 

 sile sporangia in a non-soral, acrostichoid manner, covering the entire lower sur- 

 face of sphenopterid or pecopterid pinnules. The sporangia are considered exan- 

 nulate (Kidston, 19 23), but as in Stellatheca , an apical plate and longitudinal de- 

 hiscence have been described (Danze\ 1956). 



The following spore data can be added to the above generic summary: Spores 

 are either trilete, circular in transverse plane, laevigate, and 70 to 91 [im in diameter 

 or trilete, triangular, rugulate, and 23 to 35 ym in diameter. 



Stratigraphic range: Westphalian B to Lower Permian. 



Geographic distribution: Illinois and Pennsylvania (U.S.A.); Nova Scotia 

 (Canada); Pas-du-Calais (Northern France); Derbyshire, Nottingham, and Yorkshire 

 (England); Thuringia (Germany). 



Two species of Mvriotheca . M. scaberrima (Lesquereux) Sellards, 1902, 

 and ^ arnoldi sp. nov. Pfefferkorn (p. 15), are known from the United States and 

 four from Europe (table 2). The genus can be divided into two distinct groups. One 

 group is represented by M. desaillyi Zeiller. 1883, and M. scaberrima , which are 

 characterized by small sporangia (0.25 to 0.4 mm), many sporangia per pinnule 

 (50), and small, triangular, rugulose-verrucate spores (20 to 35 ^m) . The other group, 



