i54 STUDIES IN FOSSIL BOTANY 



Before leaving the subject of the anatomy of the 

 Lepidodendroid stem, it is of some interest to note that 

 in Lepidophloios fuliginosus (Williamson), a species which 

 resembles Lepidodendron Harcourtii so closely that for 

 many years they were not distinguished, a certain amount 

 of secondary xylem was formed. It was, however, 

 much less regular than in the other species which show 

 it, such as Lepidodendron selaginoides or L. brevifolium. 

 In L. fuliginosus the cambium was an anomalous one, 

 arising irregularly in various parts of the phloem-zone 

 and pericycle. It produced a good deal of secondary 

 parenchyma, among which there are usually scattered 

 groups of wood ; the secondary tracheides have a very 

 sinuous and irregular course. In some cases tracheides 

 appear to be altogether absent from the secondary 

 zone. We may regard this species (which, from the 

 form of its leaf-bases, must certainly be referred to 

 Lepidophloios, as first pointed out by Cash and Lomax 

 in 1 8 go) as exhibiting either a primitive and rudi- 

 mentary or a reduced form of secondary growth. In 

 a rather doubtful species, Lepidodendron intermedium, 

 there is a similar mode of secondary thickening ; this 

 form derives its specific name from combining to some 

 extent the characters of Lepidophloios fuliginosus and 

 Lepidodendron selaginoides. 



Two new cases have recently been described in 

 which the external features of a petrified specimen are 

 preserved, so as to allow of its reference to a definite 

 species, based on the superficial characters, while at the 

 same time the internal structure can be investigated. 

 In a stem clearly referable to Lepidodendron obovalum, 

 Sternb., various details of the anatomy, and especially 



