16 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 463 



quite extensive (Jongmans, 1957, p. 181). Sterile foliage is called Alloiopteris 

 H. Potonie, 1897, and fructifications are called Corynepteris . Daber (1955) 

 has suggested Saccopteris Stur, 1883, a younger synonym of Corynepteris , as 

 the name for the entire plant. 



The description below is based on one fertile specimen, part and counter- 

 part (C 10814), from Mazon Creek, Illinois. The sori were covered by the carbona- 

 ceous film of the lamina, which was removed in order to obtain spores. The soral 

 structure was not observable in detail, but there is no doubt about the generic 

 assignment to this rather homogeneous genus. 



Corynepteris (ex Alloiopteris) cf. erosa (Gutbier) Kidston 1887 



pi. 7, figs. 1-6 



Description. — The preserved part of the pinna is 6 cm long and 5.5 cm 

 wide with both sides incomplete. Twelve lateral pinnae on each side are more 

 than 2.8 cm long and 4 mm wide. One of the basal pinnules (anadromic?) is 

 aphleboid (pi. 7, fig. 2). 



Spores are trilete and circular in equatorial outline and have secondary 

 folds. Laesurae are straight and extend three- fourths the length of the spore 

 radius. The commissure is usually distinct and the labra are up to 1.5 ^m wide. 

 The proximal and distal faces are covered with widely spaced spines and setae 

 up to 3 urn long and 1.5 M-m wide. Extending beyond the spore outline are 2 5 to 

 35 projections. The spore wall is 1.5 to 3.0 urn thick. The diameters of 26 

 specimens range from 38 to 80 M-m, with an average of 55 y-m. 



Discussion.— The specimen described above is most similar to Alloiopteris 

 erosa because it has a few sharp indentations on pinnules and the pinnules are 

 separated only near their tips. A. angustissima, which is similar to C 10814 

 in some respects, has smaller pinnules that are clearly separated from each other. 

 Specimen C 10814 somewhat resembles A. cristata , but aphleboid pinnules are 

 lacking in that species (Nemejc, 1938). 



The spores of Corynepteris cf. erosa are correlated with Apiculatisporis 

 setulosus (Kosanke) Potonie' and Kremp, 1955, and are compared with the holotype 

 and other specimens found in Illinois. A. cf. setulosus of Potonie and Kremp 

 (1955) is apparently coarser and more densely ornamented than A. setulosus . A. 

 setulosus is a minor constituent in the spore floras but ranges throughout Penn- 

 sylvanian strata of the Illinois Basin. Corynepteris cf. erosa is also very rare. 



Spores in situ from three other species of Corynepteris have been described. 

 Kidston (1923) illustrated and described the spores of C_. sternbergii as circular, 

 triradiate, papillose, and 55 to 58 ym in diameter. From a separate preparation 

 made from Kidston' s material, Potonie' (1967) interpreted the ornamentation of the 

 spores as conate. The specimen of C_. sternbergii examined by Brush and Barg- 

 hoorn (1964, 1965) bore triradiate, thick, psilate or finely foveolate spores 50 

 to 57 ym in diameter. Moore (1946, 1965) found triradiate, spinose spores having "an 

 annular wing" in a fertile specimen identified as Corynepteris . R. and W. Remy 

 (1957) reported that the spores derived from C_. silesiaca R. and W. Remy, 1955, 

 are 70 to 80 ym in diameter and have long trilete rays and a granulose exine. 

 Potonie (196 2) concluded that the exines of the Remys' specimens are covered with 

 verrucae rather than grana and compared them with Verrucosisporites verrucosus 

 (Ibrahim) Ibrahim, 1933. From present information, the spores of Corynepteris 



