OF THE BRITISH COAL MEASURES. S 
specimens from the same locality, figures a complete stele, but no details are 
given, and beyond confirming the general agreement with other species 
referred to the genus, there is nothing to be said. The plant is apparently 
of Middle Coal-Measure age. 
Williamson’s Lower Carboniferous species H. Grievii is too well known 
to need any discussion here. It may, however, be convenient shortly to 
recapitulate the principal characters : 
Peripheral xylem-strands not sharply delimited. 
Primary centrifugal wood of the bundles well developed. 
‘Secretory sacs” scarce or absent. 
Sclerotic plates (in the form of thin dises) present in the cortex, but not in 
the pericycle. 
Leaf-trace single and a single bundle in the petiole. 
Leaf-bases large and decurrent. 
Foliage probably that of Sphenopteris elegans. 
This species is the type of the subgenus Hu-heterangium. I am not aware 
that the structure of any other Lower Carboniferous species has been 
described *. 
In the meantime, Renault (1869, p. 177) had described two species, under 
the names Lycopodium punctatum, Ren., and Lycopodium Itenaultii, Brongn., 
which have proved to belong to the genus Heterangium. These fossils came 
from the Upper Coal Measures of Autun. The reference to Lycopodium 
involved a misinterpretation of the structure of the specimens T, and it is 
more profitable to refer to Renault’s later description (Renault, 1896, p. 253), 
written after he had recognized the true nature of the plants. The only 
figures are those in the earlier paper. Both species are represented by small 
stems, 5-5-6 mm. in diameter. //. punctatum has a certain amount of 
secondary wood and bast, which are absent in H. Renaultii; it is possible, us 
Renault pointed out, that the latter may merely be a younger condition of 
the former (Renault, 1896, p. 256). 1 examined the original preparations 
at Paris in 1905, but at that time my attention was not directed to the points 
which now seem most critical. H. punctatum, especially, bears a close 
resemblance to our H. tilicoides; it has, for example, large medullary rays, 
which are dilated in ihe phloem-zone (Renault, 1869, pl. 12. fig. 3; pl. 13. 
fig. 4). The leat-traces are said by Renault (1896, p. 254) to pass out 
opposite the rays, a statement which is scarcely confirmed by the figure (1869, 
pl. 12. fig. 1). Renault gives no definite information as to the position of 
ihe protoxylem, merely stating that the attenuated peripheral extremities 
of the vascular groups are occupied by rayed tracheides and spiral elements 
(trachées). 
* Prof. T. Johnson's species, H. Aibernicum, is based on external characters only (Johnson, 
1912). 
1 E. Williamson & Scott, 1896, p. 771. 
