40 



PALEOZOIC FOSSIL SPORES 



Affinities. — Spores of this genus have 

 not been recognized in connection with 

 fructifications. This is surprising in view 

 of their frequence in coal. They have 

 been roughly designated as "biconcave," 

 "salvershaped" and as "splint micro- 

 spores" by Thiessen and his co-workers 

 (Thiessen and Wilson, p. 9, 1924; Thies- 

 sen, 1930; Sprunk, et al, 1940) and can be 

 recognized by their characteristic "dumb- 

 bell" shape in cross section.^ 



Modern methods of study may be ex- 

 pected therefore to disclose definite evi- 

 dence of the relationship of this group. 

 Their structure is so unusual that it seems 

 evident that a single homogeneous group 

 of plants for the most part is represented. 



Raistrick's Type A spores (Raistrick 

 and Simpson, 1933) apparently are nearly 

 entirely referable to Denso-sporites. His 

 A„ Ae, (1934) and A,o (1937, 1938) 

 also are probably congeneric and, if so, 

 appear to be the most bizarre of any in 

 the genus. Possibly the A3 spores (Rai- 

 strick, 1937; Knox, 1938) are least as- 

 suredly related to this group. Knox's Type 

 Cg (Knox, 1942) possibly might be placed 

 here though its morphologic interpreta- 

 tion is somewhat uncertain due to its un- 

 usual type of equatorial development. 



Remarks. — Six species are now included 

 under Denso-sporites and it seems that a 

 good many more will need be distin- 

 guished. Raistrick's A5, Ag, and A^q 

 types are worthy of specific distinction. 

 The generic name, while perhaps of un- 

 desirable construction, is not in conflict 

 with any others that have been proposed 

 and thus is entirely valid. 



As mentioned previously, the spores 

 are widespread and very abundant in 

 splint coals. It has been suggested that 

 a special type of vegetation was respon- 

 sible for this type of coal but such can 

 hardly be the case, since recognizable splint 

 coals are also found that are so much 

 younger that floral similarities cease (cf. 

 Thiessen and Sprunk, 1936). White (in 

 discussion of Thiessen, 1930, p. 672) 

 doubts that the presence of a certain type 

 of plants is responsible for forming this 

 type of coal. The coincidence of occur- 

 rence between Denso-sporites and Pale- 

 ozoic splint coal nevertheless seems 

 unaccountably high and additional infor- 



8 Thiessen has also designated some spores not referable 

 to Denso-sporites as "splint spores." 



mation about these spores may reflect 

 importantly, although indirectly, upon the 

 problem of splint coal formation. 



1. Denso-sporites annulatus (Loose) S. 

 W. and B., comb. nov. 



Sporonites annulatus Loose, 1932, Neues 

 Jahrb. Beilage-Band 67, Abt. B, p. 451, pi. 

 18, fig. 44. 



Zonales - sporites annulatus (Loose) 

 Loose, 1934, Inst. Palaobot. Arb., vol. 4, 

 no. 3, p. 151.10 



2. Denso-sporites covensis Berry, 1937, Am. 

 Midland Naturalist, vol. 18, p. 157, fig. 11. 



Note. — Although serving as genotype, the spe- 

 cific characteristics of this form are inadequately 

 known. 



3. Denso-sporites densus Berry, 1937, Am. 

 Midland Naturalist, vol. 18, no. 1, pp. 157-8, 

 fig. 7. 



4. Denso - sporites (?) indignabundus 



(Loose) S. W. and B., comb. nov. 



Sporonites indignabundus Loose, 1932, 

 Neues Jahrb. Beilage-Band 67, Abt. B, p. 

 451, pi. 19, fig. 51. 



Zonalcs-sporites indignabundus (Loose) 

 Ibrahim, 1933, Sporenformen des Aegir- 

 horizonts, p. 32. 



Apiculati-sporites indigna bund us 

 (Loose) Loose, 1934, Inst. Palaobot. Arb., 

 vol. 4, no. 3, p. 153. 



5. Denso-sporites loricatus (Loose) S. W. 

 and B., comb. nov. 



Sporonites loricatus Loose, 1932, Neues 

 Jahrb. Beilage-Band 67, Abt. B, p. 450, pi. 

 18, fig. 42. 



Zonales-sporites loricatus (Loose) 

 Loose, 1934, Inst. Palaobot. Arb., vol. 4, 

 no. 3, p. 151. 



6. Denso-sporites (?) quadratus Berry, 

 1937, Am. Midland Naturalist, vol. 18, p. 

 158, fig. 10. 

 Note. — A very problematic form. 



Genus Cystosporites Schopf, 1938 

 Plate 1, figures 10-lOb 



Symmetry. — Spores radial, trilete. 



Form and size. — Variable depending on 

 development. Fertile members relatively 

 enormous, sack-like, elongate, sometimes 

 attaining a length of more than a centi- 

 meter and about half as broad. Abortive 

 forms variable in development, charac- 

 teristically ranging from as small as one- 



10 Since Loose recognized the rather significant distinc- 

 tion between Denso-sporites and the zonate forms, in a 

 footnote appended to his article he suggested "einer Unter- 

 abteilung Annulati-sporites" for D. annulatus and D, 

 loricatus. Because he did not adopt the name, "Unter- 

 abteilung Annulati-sporites" is invalidly published, at 

 least in the sense of a generic designation. 



