Manchester Memoirs, Vol. li. (1907), No. 1&. 3 



L. fuliginosuni, Will., and L. Wunscliianum, Will. (Seward, 

 '99), in addition to L. Harcourtii. 



Williamson then describes the structure of the Dules- 

 gate branches in some detail. 



He criticises Brongniart's conclusion, derived from a 

 study of the type of L. Harcourtii, that the outer cortex 

 was sharply separated from the middle cortex, and brings 

 forward his small branches to shew that the passage was 

 gradual. 



The uniform character of the outer cortex of L. 

 Harcourtii, Witham, thus implicitly denied by William- . 

 son, seems to be one of the characteristics of the species. 



In fig. 3, Williamson represents the largest branch 

 of L. Harcourtii with which he was acquainted. It was 

 derived from an unknown horizon at Airdrie, and so far 

 as I can judge from an examination of a polished surface 

 of the block, is really L. Harcourtii. Williamson notes 

 that its outer cortex differs from that of his small stems 

 in being more uniform. 



Williamson then goes on to consider the leaves of 

 L. Harcourtii {i.e., the leaf bases of L. Hickii). 



His description of these, though incomplete, is quite 

 accurate, except that the leaf base is described upside down. 



This error was corrected by Williamson in a note to 

 the Royal Society in 1894. 



Williamson then describes what he considers is a 

 halonial branch of L. Harcourtii. 



This branch is L. Hickii, and the correctness of the 

 application of the term halonial in this case will be con- 

 sidered below. 



In the above account of Williamson's memoir, I have 

 referred to the different tissues under the terms I shall 

 use in the description of L. Hickii. They compare with 

 Williamson's as follows : — 



