DESCRIPTIONS 



15 



pendage or ''heel", strengthened with 

 thick sub-dermal sclerenchyma, is a 

 noteAvorthy characteristic of this species. 

 The specific name '^ oedipternum^\ i. e., 

 swollen heel, refers to this feature. The 

 lamina proper is exceptionally short 

 (about 3 mm.), broad, and turned 

 sharply upward forming about an 80° 

 angle with the pedicel. A reconstruction 

 of a megasporangiate sporophyll of this 

 species is shown in text figure 2. 



The megasporangium provides the 

 significant characteristics identifying 

 the genus and consequently the holotype 

 of the new species is chosen from the 

 megasporangiate cone material. There 

 can be no doubt that the associated 

 microsporangiate and megasporangiate 

 cones belong to the same species. How- 

 ever, no organic connection exists be- 

 tween the different cones, and they are 

 inherently different. There is no basis 

 for comparison of certain specific de- 

 tails (chiefly spores and sporangia) of 

 the megasporangiate and microsporangi- 

 ate cones. Thus, since objective proof 

 of identity is lacking to this degree, a 

 minor taxonomic distinction is adopted 

 and cones of the different sexes are 

 referred to separate forms within the 

 species. 



Forma megalophorum, forma nov. 



PI. 1, figs. 1-4; pi. 2, figs. 1-5; pi. 3, figs. 1-9; 



pi. 4, figs. 1-5; pi. 5, figs. 2, 6. 



Cones as previously described, bearing 

 megasporangia. Sporangia tapering, 

 3%-4 mm. broad adjacent to the cone 

 axis; up to 5% mm. broad near the 

 distal end. Sporangia are about 5 mm. 

 long and average about 2.7 mm. high. 

 The greater distal breadth is chiefly 

 due to the occurrence of keel-like pro- 

 jections of tissue low on both sides of 

 the megasporangia giving them a some- 

 what triangular shape in cross-section. 

 These lateral keels flare distally, then 

 turn sharply upward and converge at 

 the upper distal tip of the sporangium 

 to produce a typical up-pointed "toe" 

 effect, as seen in radial section. Spor- 

 angia are covered with the characteristic 

 prismatic or palisade layer of cells as 

 in Lepidostrohus. The prismatic cell 

 layer varies in thickness, being consid- 



erably thinner in two or three areas on 

 top of the sporangia and below on both 

 sides close to the pedicel attachment. 

 No other mechanism of dehiscence is 

 provided. The sporangial interior is 

 filled by parenchymatous tissue which 

 surrounds the eight megaspores on all 

 sides. Megaspores are large, approxi- 

 mating 2 mm. in diameter, radially 

 symmetrical, varying in form from 

 plano-convex to strongly concavo-con- 

 vex. Spores adorned only by a cellular 

 "ramentum" borrowed from the intra- 

 sporangial tissue; spinous or other ap- 

 pendages absent. Gametophytes are 

 present within some of the megaspores. 

 The sporangia in these instances are 

 more or less disorganized and broken. 

 A single short-necked pyriform arche- 

 gonium is formed directly below the 

 spore apex; the venter is about 250 ji 

 in diameter. 



The holotype of Mazocarpon oedipter- 

 num and of forma megalophorum is that 

 illustrated in plate 1, figures 1-4; plate 

 2, figures 2, etc. from coal-ball 136, of 

 the Illinois Geological Survey collec- 

 tions in Urbana. 



Lam Sp K 



J/ 



Sporangium 



Fig. 2.— Reconstruction of sporophyll of 

 Mazocarpon oedipternum forma megaloph- 

 orum. SpK, sporangial keel; Lam, lamina. 



Forma microphorum, forma nov. 

 PI. 4, figs. 6-8; pi. 5, figs. 1, 3-5. 



Cones, as previously described for 

 this species, bearing microsporangia. 

 Sporangia less inflated than in forma 

 megalophorum due chiefly to absence of 



