28 



PENNSYLVANIAN SPORES OF ILLINOIS 



exist in the "American Mesozoic and Ter- 

 tiary coals." In addition to the five modern 

 genera listed by Wilson and Webster, Olof 

 Selling (1946) lists 20 other genera of 

 pteridophytes from Hawaii which are def- 

 initely monolete and thus of the Laevigato- 

 sporites type. Selling's excellent monograph 

 establishes without question the existence 

 of numerous modern monolete bilateral 

 spores. Apparently monolete bilateral 

 spores originated in very early Pennsyl- 

 vanian time and may possibly have a con- 

 tinuous range to the present day. The first 

 known definite occurrence of spores of this 

 type in Illinois is in Reynoldsburg coal bed. 

 A fragment of a spore coat which may be of 

 this type has been observed in the Wayside 

 coal bed (lower in the section). The thin 

 coal beds of the upper Mississippian should 

 be searched for spores of the Laevigato- 

 sporites type. If spores of this type are not 

 found, there was a tremendous floral change 

 between Pennsylvanian and Mississippian 

 time. The probability of this change is 

 supported by the fact that Laevigato- 

 sporit.es is generally the dominant small 

 spore type throughout the Pennsylvanian of 

 Illinois. 



The parent plant or plants of the spores 

 classified under the genus Laevigato-sporites 

 are unknown. It is surprising that so little 

 is known in view of the abundance of spores 

 of this type. The spores of a calamarian 

 fructification (Reed, 1938) and of Zeilleria, 

 a fern (Florin, 1937), are possibly of this 

 type. Suggested affinities based on modern 

 plants strongly indicate a relationship with 

 the pteridophytes. 



The spores of the genus Laevigato- 

 sporites are perhaps the easiest to identify 

 generically. This is because they possess a 

 monolete mark and bilateral symmetry. 

 Classification of the ornamented forms is 

 generally readily accomplished. However, 

 classification of the levigate forms presents 

 a perplexing problem. The known size 

 range of the genus is from 14 microns in 

 L. Thiessenii to 150 microns in L. ro- 

 bustus sp. nov. In the size range of slightly 

 under 20 microns to 30 microns there are 

 two species: L. minimus and L. minutus. 

 L. minimus is levigate and readily distin- 



guished from L, minutus, which is punctate, 

 providing overmaceration has not reduced 

 the ornamentation. There appears to be a 

 continuous size range of the levigate forms 

 from 40 to almost 150 microns, and the 

 known maximum range of the ornamented 

 species in 127 microns in L. vulgaris. There 

 are six described species, two of which are 

 known to occur in Illinois coal beds. They 

 are L. desmoinensis and L. vulgaris. The 

 latter is described as levigate to faintly 

 punctate and the other as levigate. It is 

 natural that species identification might be 

 somewhat confusing. However, judging 

 from illustrations, L. vulgaris has a much 

 coarser spore coat and on this basis species 

 separation has been made. Schopf, Wilson, 

 and Bentall, 1944, considered Loose's L. 

 vulgaris forma minor, maior and maximus, 

 1934, synonymous with L. vulgaris (Ibra- 

 him) Ibrahim, 1933. If so, automatically 

 the size range of the species is extended to 

 that of L. vulgaris forma maximus which 

 is 122 microns. Specimens from Illinois 

 which are considered to be conspecific have 

 measured more than 127 microns in the 

 longest diameter. 



The following new species have been ob- 

 served in Illinois coal beds: 



1. Laevigato-sporites latus 



2. L. medius 



3. L. obscurus 



4. L. oval is ^ 



5. L. pseudothiessenii 



6. L. punctatus 



7. L. robustus 



The following description of the genus 

 Laevigato-sporites is based upon the pre- 

 viously described species and the seven new 

 species mentioned above: spores are bilater- 

 al, monolete, bean-shaped to broadly bean- 

 shaped, sometimes approaching an oval 

 shape (L. latus sp. nov.) ; elongate oval to 

 broadly oval in plane of longitudinal sym- 

 metry, round or oval in transverse plane. 

 Folding occurs in certain species without 

 definite patterns. The known size range 

 from 14 to 150 microns in longest diameter. 

 Ornamentation levigate, punctate, apicu- 

 late, verrucose, obvermiculate to faintly 

 reticulate. Suture always monolete and 

 linear, which is less than half to three- 



