38 



ILLINOIS STATE GEOLOGICAL SURVEY 



body is round to oval in outline; flange, 

 when present, is generally widest opposite 

 trilete rays and, therefore, more or less tri- 

 angular in outline. The trilete rays are 

 long relative to spore body diameter. Spore 

 surface is smooth to reticulate. Schopf 

 (1938) noted that these spores are similar 

 to those of herbaceous lycopods such as 

 Selaginellites and Lycopodites and to those 

 of modern heterosporous lycopods. 



Chaloner (1954a) confirmed the gen- 

 eral equivalence of the Triangulati and the 

 herbaceous lycopods in his description of 

 Triletes triangulatus-type megaspores and 

 Cirratriradites annulatus-type microspores 

 from Selaginellites suissei cones. Subse- 

 quently Hoskins and Abbott (1956) iso- 

 lated T. triangulatus-type megaspores and 

 C. annulatus-type microspores from S. eras- 

 sicinctus. 



The stratigraphic occurrence and rela- 

 tive abundance of triangulate megaspores 

 approximately parallels that of microspores 

 of Cirratriradites as reported by Kosanke 

 (1947) . Triangulate megaspores are most 

 abundant in the older coals of the Trade- 

 water Group. Although Cirratriradites ap- 

 parently is not represented in coals of the 

 Caseyville Group, triangulate spores are 

 present. If those Mississippian small spores 

 referred to Cirratriradites by Hoffmeister, 

 Staplin, and Malloy (1955) truly are allied 

 within this genus, then triangulate mega- 

 spores also should be present. As yet, none 

 has been found in coal beds in the Missis- 

 sippian Chester Series. 



Triletes triangulatus Zerndt, 1930 

 (sensu Dijkstra, 1946) 



Plate 10, figures 1-10 



1930 Triletes triangulatus I, II, Zerndt (1930c), p. 



51-54; pi. 7, figs. 19-33. 

 1946 Triletes triangulatus Zerndt, in Dijkstra, p. 



52-54; pi. 4, figs. 24, 25, 27-31, 33, 34. 



Description. — Spores of medium size, tri- 

 lete, generally compressed proximo-distally, 

 from 410 to 1076^ in total diameter (in- 

 cluding flange) . Spore body round to very 

 slightly rounded subtriangular in outline, 

 originally somewhat oblate, from 395 to 

 640 /a in diameter. Trilete rays distinct, ex- 

 tending to margins of flange (pi. 10, fig. 



10) . Lips membranous and commonly pli- 

 cate (pi. 10, fig. 7), up to 100 /x in height. 

 Suture extending only about half way from 

 apex to body margin. Contact areas granu- 

 lose to ornamented with irregular ridges 

 radiating from apex (pi. 10, fig. 7) to re- 

 ticulate (pi. 10, figs. 8, 10) . Flange extend- 

 ing away from spore body 18 to 267 p at 

 corners, widest opposite rays causing over- 

 all triangular outline of proximo-distally 

 compressed spores. Flange appear- 

 ing pleated (pi. 10, fig. 10), to striate, to 

 reticulate (pi. 10, fig. 6) , often bordered by 

 a narrow lighter-appearing rim, as illus- 

 trated by Schopf (1938, pi. 4, fig. 3) and 

 Chaloner (1954a, figs. 2, 3) . Distal orna- 

 mentation consisting of a perisporal reticu- 

 late network, varying considerably in mesh 

 size (pi. 10, figs, lb, 2b, 3, 4b, 5) . 



Spore body coat granulose, from 10 to 

 26 fx thick, enclosing a folded inner mem- 

 brane, generally of triangular outline. 

 Inner membrane characteristically orna- 

 mented with small papillae (pi. 10, fig. 9) . 



Discussion. — These spores were described 

 in detail by Schopf (1938), Dijkstra 

 (1946), Guennel (1954), and Potonie and 

 Kremp (1956). Potonie and Kremp (1956) 

 distinguished several species (included 

 within Dijkstra's circumscription of Tri- 

 letes triangulatus) on. the basis of total size 

 and character of distal ornamentation. 

 Both detailed biometric analyses and cone 

 studies are needed to substantiate such a 

 subdivision if such speciation is to have tax- 

 onomic meaning. Guennel (1954) pointed 

 out that the distal perisporal membrane is 

 somewhat elastic and may cause reticula- 

 tions to vary in size. 



According to Guennel (1954) the spore 

 body, except for the contact areas, is cov- 

 ered with a perisporal membrane that 

 forms the distal reticulations, the flange, 

 and the trilete rays. He did not note the 

 presence of proximal reticulations such as 

 were described by Schopf (1938) . In the 

 present investigation, spores with distinct 

 proximal reticulations seemed to be most 

 conspicuous in the Harrisburg (No. 5) , 

 Springfield (No. 5) , and Herrin (No. 6) 

 Coals. In general most variations of distal 

 ornamentation are present in any one coal 



