20 



ILLINOIS STATE GEOLOGICAL SURVEY 



An extreme development of the cup-shaped 

 tip is shown by a small, probably immature 

 spore (pi. 1, fig. 4). Some of the megaspores 

 described by Horst (1955) as T. subpilosus 

 may be similar to those of T. subpilosus 

 forma major. 



Previously Reported Occurrences. — Spores 

 of Triletes subpilosus forma major have 

 1 ( ( i reported from the Namurian A, B, 

 and C of Turkey by Dijkstra (1952b), from 

 the Namurian of Scotland by Dijkstra 

 (1957), from the Dinantian and Namurian 

 (?) of Scotland by Chaloner (1954b), and 

 from the lower part of the Chester Series 

 of Indiana by Chaloner (1954b). 



Occurrence. — Megaspores of Triletes sub- 

 pilosus forma major are the dominant and 

 characteristic megaspores of upper Missis- 

 sippian coals. They are: 1) abundant in the 

 coal in the Bethel (Mooretown) Formation 



(maceration 943) from Kentucky; 2) pres- 

 ent in the coal in the Bethel (Mooretown) 

 Formation of Indiana (macerations 834, 

 832, 468) ; 3) abundant in the coal in the 

 Hardinsburg Formation (maceration 810) 

 of Kentucky; 4) present in the coal in the 

 Hardinsburg Formation (maceration 166), 

 in the coal in the Tar Springs Formation 

 of Scottsburg, Kentucky, and in the coal in 

 the Vienna Formation (maceration 758) 

 of Illinois; 5) abundant in the coal in the 

 Vienna Formation of Illinois (macerations 



168, 764, 842, 765, 687 A-B) and abundant 

 to present in the Degonia Formation 



(macerations 143, 200) . 



Triletes horridus (Zerndt) Schopf, 



Wilson, and Bentall, 1944 (sensu Dijkstra, 



1946) 



Plate 2, figures 6-12; plate 3, figure 1 



1934 Lagenicula horrida Zerndt, p. 25-26, fig. 11; 



pL 28, figs. 1-5. 

 1944 Triletes horridus (Zerndt) Schopf, Wilson, 



and Bentall, p. 22. 

 1946 Triletes horridus (Zerndt) Dijkstra, p. 45- 



46; pi. 12, figs. 129-136. (Dijkstra 's synonvmy, 



excluding Lagenicula I var. major of Ben- 



nie and Kidsion, accepted.) 

 1950 Lagenicula horrida Zerndt, in Arnold, p. 81- 



82; pi. X, figs. 1-5. 

 1955 Lagenicula horrida Zerndt, in Potonie and 



Kremp, p. 119-120; pi. 20, fig. 4. 



Description. — Megaspores of medium 

 size, more or less bottle-shaped with ex- 

 panded apical prominence, usually com- 

 pressed laterally; maximum equatorial di- 

 ameter, measured perpendicular to spore 

 axis, from 555 to 1305 ^ (mean 925 p for 34 

 specimens). Apical prominence well devel- 

 oped, from 180 to 350 ^ in height from base 

 of lip and up to 400 ll in width; lips gener- 

 ally open. Trilete rays one-third or less of 

 the spore radius; contact areas occupying 

 one-half or less of the proximal hemisphere. 

 Contact areas and lips occasionally bearing 

 a few tiny spines. 



Distal spore coat ornamented with widely 

 spaced spines from 50 to 160 ^ in maximum 

 length and from 15 to 60 ^ in width. Spines 

 extending from rather expanded hollow-ap- 

 pearing bases, tapering to a fine point, 

 sometimes ball-tipped and recurved, snorter 

 and more closely spaced at the margins of 

 the contact areas. Small, acuminate subsid- 

 iary spines, 5 to 30 ^ in length and 3 to 15 ^ 

 in width, generally present among the 

 longer distal spines. 



Spore coat punctate or minutely meshed, 

 7 to 22 ix thick, generally thicker than 15/x, 

 thinnest on contact areas, yellowish orange 

 to reddish brown by transmitted light. 



Discussion. — Although these megaspores 

 of Triletes horridus have a larger size range 

 than that given by Dijkstra (1946), the 

 spores correspond in their general morphol- 

 ogy, especially in the expanded, often open, 

 flaplike lips. Practically all the megaspores 

 of T. horridus seen during this study pos- 

 sess, in addition to the large distal spines, 

 small, pointed, subsidiary, distal spines. 

 The presence and abundance of these small 

 excrescences generally is regarded as one of 

 the most variable features of ornamentation 

 of T. horridus megaspores. The subsidiary 

 spines have been mentioned by Zerndt 

 (1937a) and illustrated by Arnold (1950). 

 Arnold noted their occurrence on about 80 

 percent of the specimens he examined. 

 Chaloner (1953b) described the T. horri- 

 <te-type of megaspore from Lepidostrobus 

 dubius and noted that megaspores of some 

 cones have an abundance of subsidiary 



