90 Proceedings of the Boyal Physical Society. 



leaf-scar of Lcpidodcndron, which I made in the paper 

 already referred to. In my previous communication it was 

 stated on p. 173, " Leaf- base attached to the whole area of 

 the leaf-scar (including the * field ')." That portion of the 

 leaf-scar which is known as the "field" really belongs to 

 the cortical system, of which it is in fact a cushion-like 

 elevation. The true leaf-scar is only the small shield-like 

 disk, which bears the vascular and the two lateral cicatri- 

 cules. These two "lateral cicatricules " have no connection 

 with the vascular system, and are probably glandular. 



11. SiGILLARIA. 



In my previous memoir I placed in SiyUlaria, nnder the 

 name of SiyUlaria discojjhora, Konig, sp., the plant origin- 

 ally figured by Konig as Lepidodendro7i discoj^horum} This 

 is identical with Lindley and Hutton's Ulodendron minus.^ 

 My reason for placing this plant in SiyUlaria was the 

 structure of the leaf-scar, which I stated on p. 178 (/. c.) 

 possessed, as had been figured by Sir William Dawson, a 

 central and two lateral cicatricules ; ^ and though I had not 

 observed them personally, I had no reason to doubt the 

 accuracy of this writer's observation. In reviewing my 

 paper, Mons. Zeiller * gives his reasons for doubting the 

 accuracy of the figure given by Dawson, in wdiich the three 

 cicatricules were shown, especially founding his opinion on 

 the fact that Dawson states in the description of his species 

 — Lejndophloios parvus = S, discophora — that the vascular 

 points are obscure. 



I received, however, in 1886 from the Rev. David Lauds- 

 borough, Kilmarnock, to whom I am indebted for many 



^ Konig, Icones fossilium sectiles, pi. xvi., fig. 194. 



* I should say here that although this latter name is the older one, it has 

 been so much confused by authors, expediency almost demands that it be 

 subordinated to the name given by Konig, from the use of which no confusion 

 or misunderstanding can arise. 



3 "Acadian Geology," 2d ed. 1868, p. 455, fig. clxx., g^. 



^"Presentation d'une brochure de ^l. Kidston sur les Vlodcndron et 

 observations sur les Genres Vlodcndron et Boi/irodcndron," Bull, de la Soc. 

 Geol. de France, 3^ ser., vol. xvi., p. 168 (1885). 



