144 Transactions of the [Ki\!STilTo. 



III. — On the Structure of the Stems of the Arborescent Lyccpo- 

 diocese of the Coal-measures. By W. Caeruthees, F.L.S., 

 F.G-.S., i3otanical Department, British Museum. 



III. On the Nature of the Scars in the Stems of Ulodendron, 

 Bothrodendron, and Megaphftum ; ivith a Synopsis of the 

 Species found in Britain. 

 (Communicated to the Eoyal Microscopical Society by the Tresident.) 

 (Continued from Vol. II., page 227.) 



These genera are founded on stems wliicli liave large scars in longi- 

 tudinal series on the two opposite sides of the stems. Of one of 

 these the authors of the ' Fossil Flora' (plate Isxx.) said, many years 

 ago, that " of all the anomalous forms that the Coal-measures have 

 afforded traces this is perhaps the most remarkable." The various 

 and very opposite opinions which have been, and still are, enter- 

 tained in regard to them fully justify this statement. For several 

 years my ati3ention has been directed to the group, and during that 

 time I have lost no opportunity of examining specimens in diif'erent 

 collections in Britain. I have, besides, carefully examined a large 

 series — most probably the largest anywhere to be found — in the 

 British Museum. The interpretation which I have been led to 

 adopt is somewhat different from that of my predecessors, but before 

 explaining it and the data on which it rests, it will be well to give 

 an historical sketch of the different opinions hitherto entertained. 



The earhest notice of these fossils with which I am acquainted 

 is by Steinhauer, in the ' American Philosophical Transactions ' 

 (vol. i., New Series, 1818), where he gives a very accurate drawing 

 and description of tl. parmatus. He cautiously considers that there 

 is not sufficient data to form any satisfactory idea of the affinities 



EXPLANATION OF PLATE XLIII. 



-Ulodendron Taylori, sp. nov. Natural size. From a specimen from Bath- 

 gate, Liulitligowshire; in the British Museum. 



-U. ]m7nilum, sp. nov. Natural size. From a specimen from the York- 

 shire Coal-field, in the British Museum. 



-U. minus, Lindl. and Hutt. Section of tlie inverted cone of an aiirial 

 root in a sandstone cast of the stem, showing the depth to which the 

 articulating surface penetrated the stem. From the collection of 

 Ch. Peach, Esq. 



-U. inajii.s, Lindl. and Hutt. Scar and leaves, natural size. From tlie 

 cast of a specimen found near Swansea by Mr. Lucas ; in the British 

 Museum. 



-U. tumidum, sp. nov. Stem reduced one-third, showing the arrangement 

 of the vascular bundles for the leaves, some patches of tiie carbonized 

 remains of the bases of the leaves, and the swollen bosses from which 

 the aerial roots sprang. 



-A patch of the carbonized remains of the bases of the leaves, natural 

 size. 



-A cicatrix, natural size. 



