90 Scott and Mas ten. — The Structure of Trigonocarpus . 
trate and describe in detail the structures there referred to, to describe 
a new species of Trigonocarpus 1 , to briefly describe the specimens which 
are preserved as structureless casts and impressions and compare them 
with those in which the internal structure is preserved, and to discuss the 
probable affinities of Trigonocarpus and the general bearing of our work. 
Among the many forms of seeds which occur in the British Coal- 
Measures none are more familiar to geologists and palaeobotanists than 
the more or less triangular nut-like seeds referred to Brongniart’s genus 
Trigonocarpus. This name (or Trigonocarpum ) was originally applied by 
Brongniart, in his Prodrome Tune Histoire des Vt*gSaux f os sites 2 , to French 
specimens, on account of their characteristic three-ridged form as seen in 
the ordinary sandstone casts, and equally well in transverse sections of the 
petrified seeds preserved in the calcareous concretions of the Lower Coal- 
Measures. 
In the most common mode of preservation, the familiar three-angled 
< nuts * of the miners were long ago shown by Hooker and Binney 3 and 
by Williamson 4 to be nothing more than internal casts of the cavity of the 
seed, and to be often surrounded by a thin coaly layer which was correctly 
interpreted as the remains of the testa. These internal structureless casts 
are found in all parts of the Coal-Measures. Wild 6 instances the Peel Delf 
rock, near Worsley, in the Upper Coal-Measures, and the Bardsley Delf rock, 
near Ashton-under- Lyne, in the Middle Coal-Measures, as localities which 
have yielded a great many examples of these triangular internal casts, while 
in the Lower Coal-Measures Trigonocarpus is not uncommon in a petrified 
form. Some of the specimens exhibited at the Natural History and other 
Museums show hundreds of examples of Trigonocarpus on one slab of rock, 
and thus serve to illustrate in a striking manner the abundance of these 
seeds and of the plants on which they were borne in later Palaeozoic 
times. 
Trigonocarpus occurs also at corresponding horizons in many parts 
of Europe. The French Stephanian (corresponding to our Upper Coal- 
Measures), especially at Grand’Croix, near St. Etienne, has yielded 
numerous types of Gymnosperm seeds, many of which were originally 
described by Brongniart 6 . These silicified Carboniferous seeds from St. 
Etienne have also been studied by Renault, and quite recently by Prof. 
1 Some reason should be given for our use of the form Trigonocarpus in this paper instead of 
Trigonocarpon, which was the name used in our preliminary note. The name of this seed has, 
unfortunately, been spelt differently by different authors. Brongniart himself in his original 
‘ Prodrome ’ uses Trigonocarpum , in his 1 Tableau ’ Trigonocarpon is used, while in the memoir on 
the St. Etienne seeds the genus appears as Trigonocarpus. Lindley and Hutton used Trigono- 
carptim, while Williamson adopted Trigonocarpon. Prof. F. W. Oliver, F.R.S., in his recent papers 
on some of the French seeds uses Trigonocarpus and for the sake of uniformity among present-day 
observers we have adopted the same form. 
2 Brongniart (’28). 3 Hooker and Binney (’55). 4 Williamson (77), p. 251. 
5 Wild (’00), p. 435. 6 Brongniart (74), (’81). 
