LEPIDOPHLOIOS, AND ON THE BRITISH SPECIES OF THE GENUS. 545 



Internal Structure of Lepidophloios. 



1848. Dawes. 



Mr Dawes while describing the internal structure of Halonia, as observed in some 

 specimens in his possession, remarks : — ■" These few observations will be able to show 

 that the fossil in question belonged to the vascular Cryptogamia, and that when compared 

 with the other plants of the coal measures, the nearest affinity is with the Lepidodendron." 



1872. Binney (loc. cit.). Palceontographical Soc. 



The structure of Halonia is fully gone into by Mr Binney in this Memoir, and 

 illustrated by several plates. 



1872. Williamson. " On the Organisation of the Fossil Plants of the Coal Measures." 

 Part II. Lycopodiacece, Lepidodendron, and Sigillaria, Phil. Trans., p. 222. 



Professor Williamson here states — " I have little doubt but that the Halonia was 

 a fruit-bearing branch of a Lepidodendron, and that from each of the tubercles there 

 was suspended a cone." In a footnote, p. 222, after mentioning that the usual form of 

 Halonia regularis represented a semi- decorticated condition, he says, on p. 223, — " It 

 thus appears that these outer layers of the bark, having an aggregate thickness of from 

 three-eighths to half-an-inch, filled up the deep valleys separating the conical hillocks of 

 Halonia, and almost reduced the entire surface of the plant, when living, to a uniform 

 level.* These determinations bring the minute and geometrically arranged punctations 

 covering the surface of the Halonia into homological relations with similar markings 

 seen on other semi- decorticated Lepidodendroid plants." 



The first part of this footnote expresses exactly what is seen on specimens of Halonia 

 whose outer bark is preserved, but such specimens show that Halonia is the fruiting 

 branch of Lepidophloios, not of Lepidodendron. 



A considerable space is occupied in this Memoir with a description of the internal 

 structure of Halonia, and from the structure of the vascular bundle which passes to the 

 tubercles, Professor Williamson infers "that the vascular bundle, thus originated, proceeded 

 to some modification of a branch, but which modification was of smaller dimensions than 

 branches usually attained to, and which, consequently, requires a less abundant supply 

 of vascular tissue than ordinary bundles need. Such a modification w T ould, I imagine, 

 only be found in a Strobilus, which must be regarded as a branch that has undergone an 

 arrested development at a very early stage of its growth." 



* See the figure given in this communication, PI. II. fig. 5, which confirms this statement. 

 VOL. XXXVII. PART III. (NO. 25). 4 N 



