EXPLANATION OF PLATE 56. 
size. On comparing this scar with those upon the 
bark of Fig. 2, it may be seen that the different 
modes of articulation of the leaves with the cortical 
integument present obvious characters, on which 
specific distinctions may perhaps most easily be 
established, in this very obscure and curious family 
of extinct plants. See various figures of these leaf- 
scars in Lindley and Hutton’s Fossil Flora, Plates 
55. 56. 57. 71. 72. &c. In Figs. 2, and 2', as in 
many other species, decurrent lines are visible on 
both sides of the scar. (Original.) 
Fig. 3. Ulodendron Allanii, {nobis) scale one-fifth. 
See V. I. p. 475. Note. Drawn from a plaster cast 
of an impression on sandstone, in the Museum of 
the Royal Society of Edinburgh from the Coal for- 
mation at Craigleith. This sandstone has formed 
a natural mould on tlie outer surface of a stem, 
which has entirely perished ; our cast gives a fac- 
simile of the small rhomboidal scales, and of three 
larffe round scars on the exterior of the trunk. 
O 
This impression has been figured, in an inverted 
position, by Mr. Allan in Vol. IX. Trans. Royal 
Soc. Edin. 1823. PI. XIV. p. 236. (Original.) 
Our figure represents the trunk in its natural 
position. In the centre of each scar is a cavity, 
indicating the place of attachment of a cone. The 
upper portion of each scar is marked with furrows, 
produced by pressure of the long radiating scales 
at the bottom of the cone. This pressure has 
nearly obliterated the smaller rhomboidal scales of 
the bark, in those parts where the furrows are 
deepest; on the lower portion of the scars, the 
scales of the bark have been but slightly modified 
by pressure of the cone. 
