Notes on Trigonocarpus and Polylophospermuin. 
103 
same period as the problem whether Sternberg’s Sigillaria ocellata 
was a Cactus or a Euphorbia), we come to the definite identification 
by Hooker of Trigonocarpon as a Gymnosperm seed (loc. cit. 1855). 
This identification being based on an examination of petrified 
specimens is of definite and permanent value and differs fundamen¬ 
tally from earlier conjectures depending on casts and impressions. 
In 1873, J. S. Newberry published some interesting speculations 
as to the origin of the numerous forms of Trigonocarpon which he 
had found in the Ohio Coal-Field. 1 He was much inclined to refer 
them to Sigillaria by eliminating the other associated plants as 
inappropriate. Three years later, when so many fresh seeds had 
come to light through the agency of Grand ’Eury, Brongniart and 
Williamson, we find the last-named in doubt as to the plants that 
could have borne them. “ We have recently brought to light such 
a multitude of seeds that it becomes a matter of extreme perplexity 
to know on what stems they grew ; ” 2 and again, “ From the 
number and size of these seeds, it is evident that we have had, at 
the Carboniferous age, some fifty or sixty species of seed-bearing 
plants, of which we have as yet been unable to identify the stems 
and leaves. These seeds make an important addition to our 
knowledge of the flora of the Carboniferous age, but one which 
requires much further investigation. They will, however, abundantly 
repay the time and toil bestowed upon them.’’ 3 
In the absence of certain indications as to the origin of these 
seeds it is not surprising that some latitude should have been taken 
by Palaeo-botanists. Thus, there was the conjecture that the seeds 
belonged to an upland forest vegetation otherwise unrepresented in 
the coal. Then, on the definite reference of certain of the seeds to 
Cordaiteae, a tendency arose to regard them all as belonging 
to that ancient group of Gymnosperms. Again at one time and 
another, under various pretexts, occasional seeds have been 
conjecturally attributed to Gnetaceae and Calamitineae. However 
from the lack of definite data botanical interest has ceased for 
twenty years to concern itself with these detached bodies. Nor 
has this neglect been without compensating advantages. For the 
vegetative organs of Coal-measure plants have been exhaustively 
examined meanwhile from an anatomical point of view, and it has 
been definitely recognised on anatomical grounds alone that many 
of the fern-like plants of those times exhibited characters 
1 Geol. Survey of Ohio, Vol. I, Pt. 2, Palaeontology, p 364. 
2 Coal and Coal Plants, a lecture delivered at Glasgow, Nov. 
24th, 1875, p. 28. 
Toe. cit. p. 29. 
3 
