OF THE BRITISH COAL MEASURES. 67 
all the sections known to me is given in a footnote *. The four stems will 
be shortly referred to as 
Specimen 1 (Williamson, slide 1301 ete.). 
Specimen 2 (Williamson, slide 1302 ete.). 
Specimen 3 (Williamson, slide 1620 eto.). 
Specimen 4 (Scott, slide 1323 ete.). 
Specimen 3 is the only one which affords a fairly long series of trans- 
verse sections. I have succeeded in determining the order of the 10 sections 
(from various collections) and find it to be as follows, from below upwards :— 
Q. 60; R. 658; Q. 59; N. 12; W. 1620; W. 1624; W. 1623; W. 1625; 
Q. 58; R. 634. 
Two leaf-traces are shown ; the divergence between them would be con- 
sistent with a 2 phyllotaxis. At the bottom of the series the inner trace (T. 1) 
is scarcely beginning to leave the stele; it consists of two distinct strands 
which, however, are here almost in contact laterally (P1. 8. fig. 8, from the 
4th section). As they pass out through the pericycle they separate rapidly; 
and gradually lose their own secondary tissues, while those of the stele close 
in behind them. At the top of the series (the ninth section, Q. 58, is the last 
which shows this trace complete) the bundles are 2 mm. apart and are in the 
middle of the pericycle, in which they cause two marked projections. They 
show, however, no sign as yet of further division. 
At the bottom of the series the outer trace (T. 2) is about as advanced as 
the inner trace was in the uppermost section. In the 2nd section the two 
* [n the following list the letter W. indieates the Williamson Collection in the British 
Museum (Natural History); the letters Q. & R. the collections of the Manchester Museum, 
Q. being the Cash, R. the Hick Collection; S. indicates my own collection; and N. that of 
the Botanical Department of University College, London (Heterangium slides). 
` Specimen 1.—2 transverse sections, W. 1301; R. 632. 
Specimen 2.—6 transverse and 7 longitudinal sections. Transverse: W. 1302, 1303, 1619; 
Q. 55, R. 654; S. 237. Longitudinal: W. 1304, 1621, 1622, 1627, 1628; Q. 56, 
R. 631 (?). All these sections appear to be from the same stem, a point not 
recognised in the joint memoir (Williamson and Scott, 1895, p. 778). 
Specimen 3.—10 transverse sections: W. 1620, 1623, 1624, 1625; Q. 58, 59, 60; R. 634, 
658; N. 12. 
Specimen 4.—9 transverse and 2 longitudinal sections. Transverse: R. 633; S. 1323. 
Longitudinal: S. 238, 1324. ; 
The order of the transverse sections, so far as it could be determined, is given in 
the text. 
The above list is limited to stems from Halifax. There is a Dulesgate specimen (slides 
S. 625 & R. 639) which bears some resemblance to H. tiliæoides, but seems to be really 
referable to H. Lomavii (see pp. 77, 79, 82). 
A small stem from Halifax, collected by the late Mr. Spencer (sections S. 239, S. 1322; 
N.2 a, N. 2 b) may be a young specimen of the same species. 
