The wall of the spore is ornamented by a coarse re- 
ticulation. The wall is thick (20 to 25 micra) and is col- 
ored by a dense bituminous substance. The apex of the 
spore bears a large tetrad scar. Coal technologists have 
referred isolated spores of this type to the form-group 
Perisporozonales, and the closest resemblance is to be ob- 
served in Spore Type IX (2) or T'riletes circumtextus 
Zerndt (3). The megaspores of the strobilus from Mazon 
Creek are of the type found in Bothrodendron mundum 
(4), but this species is believed to have been arborescent. 
Comparison with Fossil Forms. 
The genus Selaginellites was founded in 1906 by Zeil- 
ler(5) for herbaceous fossil lycopods believed to be heter- 
osporous. Brongniart in 1822 (6) defined the form-genus 
Lycopodites to include the slender, dichotomously 
branched shoots which resembled the living Lycopodium 
or Selagincella. The name Selaginites has been given to 
various foliage types which appear to have been aniso- 
phyllous, but none of the so-called Selaginites are known 
from reproductive parts. 
Lesquereux (7) has described three species of Lyco- 
podites ( Selaginites ) from Morris and Mazon Creek, Ili- 
nois: Lycopodites cavifolius, Lycopodites pendulus, and 
Lycopodites Meeku. All of these are known from only 
foliage impressions. 
The various species of Selaginellites are much more 
completely known. The genotype is Selaginellites Suessa 
Zeiller (loc. cit.). The strobili were of comparatively great 
size, attaining a length of fifteen centimeters and a diam- 
eter of eight to ten millimeters. The sporophylls were 
very numerous, those near the summit of the strobilus 
bearing microsporangia filled with many microspores, 
and those in the lower part of the strobilus bearing mega- 
sporangia each with sixteen to twenty-four megaspores. 
[119 | 
