OF THE BRITISH COAL MEASURES. 83 
roots are present; their position, unlike that of the roots in previous 
specimens, shows no relation to the leaf-traces. 
I believe that specimen 6 is part of the same stem, though the state of 
preservation is different, the phloem having collapsed. The surrounding 
objects are the same, and the structure of the stem agrees essentially, especially 
in the absence of any well-marked Sparganum hypoderma. The two sections 
W.1915 D & E each show two double leaf-traces too near together for any 
probable phyllotaxis, but possibly displaced. They are rather small bundles, 
300—410 w in diameter. The main point is that here again two double traces 
are seen in the same transverse section. 
A third section (N.3) is photographed (Pl. 2. Phot. 12). Itiscomplete, which 
the two Williamson sections are not, and probably belongs to the same stem, 
though there is no absolute proof. Two double leaf-traces are shown, at a 
divergence which may be roughly estimated at 2. One trace (T. 1) is in the 
outer part of the pericyele, the other (T. 2) may have just entered the cortex. 
The bundles of each trace are near together * and their relation to each 
other is obvious. In size they are somewhat larger than in the previous 
sections (410—490 y). 
The stem just described is a variant on the £ type first considered, though 
the distinctions are not important; the peculiarities are that two traces are 
usually seen in the same transverse section, that the two bundles of a leaf- 
trace are usually near together, that the bundles are, on the average, small, 
and their tracheides also small. It may be added that no regular relation 
appears to obtain in this case between the roots and the leaf-traces. Con- 
sidering the poor development of the mechanical tissues it is not improbable 
that the stem was of the nature of a rhizome. 
The A specimens generally establish the fact that the leaf-trace was 
eonstantly double from its starting-point in the stele outwards, the two 
bundles being often remarkably far apart. We have so far no conclusive 
evidence as to their further subdivision. It may be mentioned that in this 
species the trace-bundles carry no secondary wood out with them when they 
enter the pericycle. 
Further considerations may be postponed till we have compared the other 
forms of stem in the species. 
H. Lomaxii, Form cylindricum f. 
In the joint memoir with Williamson this form was provisionally treated 
as distinct, for it was obviously different from Æ. Grievii, with which the 
other Dulesgate specimens were at that time confused, while it was not 
* Those of the outer trace are evidently displaced, and appear closer together than in 
nature. 
T Williamson & Scott, 1895, p. 764, pl. 28. figs. 30, 31. 
