o/ Ulodendron to Lepidodendion, &,c. 171 



lateral angles sharp. The cushion on which they are placed 

 very slightly exceeds the size of the leaf-scar. The vascular- 

 bundle impression is situated a little above the centre of the 

 leaf- scar. 



Specimen No. 17. From the Oil Shales, Addiewell, Mid- 

 lothian. In the collection of the Addiewell Oil Company 

 (Calciferous Sandstone Series). PI. VI. fig. 10, 10 Z*, c, c/ 

 (fig. 10, ^ nat. size ; fig. 10 5, c, c?, nat. size) . 



Tliis specimen, which is preserved in a fine-grained bitu- 

 minous oil-shale, exhibits the termination of a branch. It 

 measures 15f inches in length and 4 inches in breadth. 

 Very little of the fossil proper is preserved, the greater part 

 of the example showing only the impression of the plant. 

 The part marked a, fig. 10, is a small portion of the outer 

 surface of the plant. That lettered 5, c, d shows the inner 

 surface of the outer cortical layer ^ and that marked e, e the 

 impression of the outer surface of the stem in the matrix. 



We must now enter more fully into the description of the 

 various parts of this instructive specimen. On the small part 

 of the fossil proper which is preserved (fig. 10 a) there is only 

 a portion of one of the Ulodendroid scars shown ; this occurs 

 as a circular depression about f inch wide. The opposite 

 and corresponding row of Ulodendroid scars occurs on that 

 part of the specimen lettered in the figure &, c, d. 1'he epi- 

 dermal layer of the bark has here adhered to the matrix, a 

 circumstance which frequently takes place in this group of 

 fossils, so that the view presented of this part is the inner 

 surface of the outer cortical layer. On this are seen the casts 

 of twelve Ulodendroid scars ; and as they are looked at from 

 the inside of the stem, they appear as elevations. In form 

 and size they vary considerably. Many of them touch each 

 other, but some are separated by a slight interval. A few 

 are almost circular, whilst others are more or less elliptical ; 

 and occasionally, when two Ulodendroid scars come in con- 

 tact, their sides become somewhat flattened from mutual 

 pressure. The largest of these scars measures transversely 

 Iyq inch, the smallest about yV inch. The scar lettered c, 

 fig. 10, is shown natural size at fig. 10 c. The whole of 

 its surface is covered with little dots arranged in spirals, some 

 belonging to series which do not converge towards the 

 umbilicus, but go past it. 



None of the Ulodendroid scars, of course, on the part let- 

 tered h, c, d show the straight or slightly bent bands on their 

 upper part, which so commonly radiate from the umbilicus of 

 Ulodendroid scars, as we are viewing the inner surface of the 

 outer cortical layer ; this also explains why the little " dots " 



