Manchester Memoirs, Vol. li. (1907), No. 13. 15 



Williamson ('93), Scott (:00), and Weiss (:02) regard 

 the projection of the tubercles above the general level of 

 the cortex as the essential point distinguishing Halonia 

 from Ulodendron. 



Kidston, on the other hand, regards the quincuncial 

 arrangement of the branch scars as of primary importance, 

 and the amount of their projection or the reverse of no 

 value. He states that Ulodendroid branches only occur 

 in Lepidodendron, Bothrodendron, and Sigillaria, not in 

 Lepidophloios (Kid., :05). 



Into the correctness of this conclusion I do not wish 

 to enter here, but Wild's Ulodendron, described in 

 Williamson's XIX. Memoir (Will, '93), certainly bears 

 typical Lepidophloios leaf bases, and has its tubercles in 

 two rows. 



Following Kidston's nomenclature, the " Halonial " 

 branches of L. Hickii should be called Ulodendroid, but 

 as I do not believe that they were fructigerous, I prefer 

 not to call them either. 



They agree with the specimen described by Carruthers 

 ('73) as " Halonia gracilis, L. & H." Kidston ('93) states 

 that this specimen is a branch of L. ophiurus, Brongt. 



It is noticeable that in L. Hickii the " Halonial " 

 branches do not seem to have been deciduous, as quite 

 long pieces are often found in connection with the stem. 



Is L. Hickii a Lepidodendron or a Lepidophloios ? 



Considerable confusion seems to exist at present as to 

 the distinguishing features of Lepidodendron and lepido- 

 phloios. Some palseobotanists (Scott, :00) seem to regard 

 the horizontal breadth of the leaf base being greater than 

 its height as a distinguishing feature. Others (Weiss, :02) 

 make the downward direction of the leaf bases a charac- 

 teristic feature. 



