«XX 
WENMTITUMERSAT S, he RARIOR SE TERR ERR RE RM ONE eA US P PRESSE RET MA 
Yr 
94 DR. D. H. SCOTT ON THE HETERANGIUMS 
In describing H. Renaultii, he makes the important remark that “on one 
side of the woody cylinder we notice two bundles which are separating from 
the axis, and in the parenchymatous part of the cortex two others which 
have already quitted it for a certain time” (1896, p. 255). It thus appears 
that this species gave off its leaf-trace bundles in pairs. He also observed 
>in the bundles. I have little doubt that both 
forms may be referred to the subgenus Polyangium, but a re-investigation 
is required. 
Another Autun species, H. Duchartre’, Ren., was originally described under 
the name of Porozylon Duchartre’ (Renault, 1879, p. 276, pl. 14. figs. 4-8) ; 
it was excluded from that genus in 1886 (Bertrand & Renault, 1886, p. 245), 
and appears as a /Jeterangium in the ‘Flore d'Autun et d'Épinac? (Renault, 
1896, p. 251, pl. 65. figs. 1, 2). The stem (6:5 mm. in diameter) has very 
much the characters of H. tiliwoides, but little beyond the wood is preserved. 
'The prineipal rays are conspieuous, dividing up the secondary zone into 
15 sectors (Renault, 1896, pl. 65. figs. 1, 2) *. Here, again, the groups of 
spiral and scalariform tracheides are described as lying at the periphery of 
the primary wood. Two bundles, widely separated, but on the same side of 
the stem, are seen in the cortex ; there can be little doubt but that they both 
belonged to the same leaf-trace. It appears, then, that this form also may be 
included under the provisional subgenus Polyangium. Renault calls atten- 
indications of “dichotomy ' 
tion (1896, p. 254) to the similarity between M. Duchartrei and H. punctatum ; 
it is possible that all the three forms just described may eventually be reduced 
to one species. 
On the other hand, a fourth Autun form, Æ. bibractense, Ren. (Renault, 
1896, p. 252, pl. 65. figs. 3-6), seems to be quite distinct. It is remarkable 
for the small size of the primary wood (1-1:5 mm. diameter) and the great 
thickness of the secondary tissues f. Parts of the phloem and the cork are 
preserved. "There are large prineipal rays as in the preceding species. 
Nothing is known of the leaf-traces. No other Heterangium has been found 
in such an advanced state of growth. 
It will be noticed that all the Autun specimens, so far as their structure is 
known, agree better with the British Cosl-Measure forms of the Polyangium 
type than with the Lower Carboniferous species //. Grievü. his is natural, 
considering their age, which is considerably later even than that of our Coal- 
Measure forms. 
We have now briefly to consider the very interesting series of species of 
Heterangium recently described by Dr. Kubart from the Ostrau beds of 
Upper Silesia (Kubart, 1908, 1911, 1914). At present only preliminary 
accounts have been published, so the data for a full comparison with our own 
* The figures of the 1896 memoir appear to be much more exact than those of 1879. 
+ Renault gives the thickness of the wood as 55 mm. I found it to reach nearly a 
centimetre in places. 
