362 Mr. R. Kidston on new 



centre, rounded, but distinct, the lower margin indented by a 

 slight sinus ; vascular cicatricules situated above the centre, 

 the two lateral lunate, the central punctiform. On the ribs 

 immediately above the leaf-scar is a slightly bent trans- 

 verse furrow. The decorticated stem is finely striated 

 longitudinally. 



Remarks. In the specimen figured on PL XI. fig. 1, the 

 ribs are 20 millim. broad ; the leaf-scars, of pyriform outline, 

 are 10 millim. in height and the same in breadth ; they stand 

 about 4 millim. apart. The slightly lunate transverse furrow 

 which surmounts them is about 10 millim. long. The outer 

 surface of the bark is quite smooth. 



The elevation of the ribs is shown at fig. 1 b. They are 

 flat, but, from the perfection with which the leaf-scars are 

 preserved, I am inclined to think that the fossil has suffered 

 little from pressure. 



This example agrees in all respects with the figure given by 

 Sauveur (without description) and that described by Boulay, 

 except that neither of these authors notes the occurrence of the 

 transverse furrow above the leaf-scar ; but the specimens 

 described by these writers do not appear to have been very 

 well preserved. 



Boulay mentions, in his description, that in his fossil the 

 cicatricules were badly preserved ; and from the slight haziness 

 which pervades Sauveur's figure, one is also led to conclude 

 that neither was it in a very good state of preservation. 



The ribs on the Scotch specimen are broader in proportion 

 to the size of the leaf-scars than in the foreign examples ; 

 but this character is evidently dependent on the age of the 

 plant. 



I have observed in specimens of Sigillaria laevigata, Brong- 

 niart, that though the ribs with age increase much in width, 

 the leaf-scars undergo little or no enlargement ; hence the 

 relative size of the leaf-scar to the width of the rib appears to 

 be of very little specific value. The distance of the leaf-scars 

 apart is also subject to much variation, even on the same 

 specimen. 



Sigillaria Walchii appears to be rare in Britain. The only 

 example I have as yet seen was communicated to me for 

 examination by Mr. J. Smith, Kilwinning, to whose courtesy 

 I am indebted for the addition of this species to our Carbo- 

 niferous fossil flora. 



Horizon. Coal-measures; roof of turf-coal. 



Locality. Kilwinning, Ayrshire. 



