13 



Residues in which spores were present but 

 not abundant were run through a vibraflute, 

 as outlined by Tschudy (I960, p. 325-326), 

 several times in order to eliminate some of 

 the fine organic debris. The plant material 

 was stained and mounted in the same man- 

 ner as the insoluble botanic remains of the 

 macerated coal. 



Percentage distribution of spore taxa was 

 determined by counting 500 spores from each 

 coal sample and 300 from each of the other 

 lithologies. Identification of species was made 

 whenever possible, but in many macerations 

 preservation was so poor that only generic 

 identifications could be made. 



which A. guerickei, a species described by 

 Horst in 1943 in a dissertation, served as the 

 type species. As the dissertation was not given 

 wide distribution, it probably should not be 

 considered a valid publication. According to 

 the International Code of Botanical Nomen- 

 clature (Lanjouw, 1961), Art. 29: "Publi- 

 cation is effected, under this Code, only by 

 distribution of printed matter (through sale, 

 exchange, or gift) to the general public or 

 at least to botanical institutions with libraries 

 accessible to botanists generally." Horst de- 

 scribed A. guerickei in the publication dated 

 1955 (p. 178) and thus validated the genus. 



Affinity. — Unknown. 



LOCATION OF SPECIMENS 

 ON SLIDES 



All specimens illustrated in this report are 

 circled in ink on the glass slides, which are 

 deposited at the Illinois State Geological Sur- 

 vey. The serial number of the Spencer Micro- 

 star microscope, whose mechanical stage was 

 used in giving the location by coordinates of 

 specimens on the slides, is 417297. 



DESCRIPTION OF 

 SMALL SPORES 



The system of spore nomenclature outlined 

 by Schopf, Wilson, and Bentall (1944) is 

 used in the following description of new T 

 genera and species and in recording previous- 

 ly described spores, except those taxa de- 

 scribed under the system proposed by Potonie 

 and Kremp and by other European workers. 

 A complete list of spore genera and species 

 observed in this study and their percentage 

 of distribution in each maceration is given 

 in the spore distribution chart (table 1). 

 Only species that required some discussion 

 are mentioned in the text. 



Genus Ahrensisporites (Potonie & 

 Kremp) Horst, 1955 



Type species. 

 Horst, 1955. 



Ahrensisporites guerickei 



Discussion. — Potonie and Kremp (1954, p. 

 155) constructed the genus Ahrensisporites in 



Ahrensisporites exertus sp. nov. 

 Plate 1, figures 1-2 



Diagnosis. — The spores are radial, trilete, 

 and more or less triangular in outline with 

 straight to slightly convex interradial sides. 

 The trilete rays are distinct, straight, and 

 more than three-fourths the length of the 

 spore radius. The kyrtomes are connected 

 on the distal surface to the arcuate folds, 

 which are 3.5 to 7 /x long and 16 to 24 /x wide. 

 A single spherical projection, about 5 /x in 

 diameter, is present near the pole on the dis- 

 tal surface. That the exine is somewhat ver- 

 rucose or rugose is suggested by irregular 

 light and dark areas that appear when the 

 specimens are viewed under high dry objec- 

 tive. The spore coat is about 2 /x thick. Di- 

 mensions (10 specimens) : size range, 32.7 

 to 41.5 it in maximum diameter; median, 



38.0 ii. 



Holotype. — Plate 1, figure 1 ; negative 6127 ; 

 Henshaw Formation, maceration 1122-G, 

 slide 8 ZB, coordinates, 126.5 X 50.3; size, 



38.1 by 36.6 /x. 



Paratype. — Plate 1, figure 2; negative 6430; 

 Henshaw Formation, maceration 1122-Q, 

 slide 17 ZB, coordinates, 145.2 X 32.5; size, 

 36.1 by 35.8 /x. 



Comparison. — Ahrensisporites exertus is 

 similar in appearance to A. guerickei Horst, 

 1955, but is smaller. A. exertus differs from 

 A. symetricus Alpern, 1959, in having a non- 

 uniformly thick, almost verrucose surface. 

 A. exertus differs from all other species of 

 Ahrensisporites by its possession of a single 

 spherical projection near the distal pole. 



