124 Mr. R. Kidston on the Relationship 



characters by wliich a specific, or even in some cases a generic, 

 determination can be made. 



In Ulodendron, on the other hand, though it is difficult to 

 account for it, decorticated and badly-preserved specimens, if 

 only they show the characteristic Ulodeudroid scar of the 

 genus, have often been regarded as in a sufficiently good state 

 of preservation, not only for generic identification, but even 

 for the creation of new species, notwithstanding that the close 

 affinity of Ulodendron and Lepidodendron, both in regard to 

 their internal structure and general characters, is fully recog- 

 nized. The form and size of the Ulodendroid scar have com- 

 monly been made the characters on which the various species 

 of Ulodendron have been founded, the descriptions generally 

 mentioning as the chief distinguishing point " scar so long by 

 so broad." Such arbitrary specific distinctions to be of any 

 value must infer that the plant sprang into existence with the 

 Ulodendroid scars fully developed. This view of course was 

 never intended by the authors who described the various 

 species characterized as indicated above ; but to make the 

 species of true value an inference of this nature is quite 

 legitimate. 



Before entering further on the discussion of this subject it 

 is desirable to give an epitome of the views which have 

 been held by the many botanists who have written on it. 

 As it is now universally admitted that Ulodendron is 

 Lycopodiaceous, no note is taken of the different opinions on 

 this point which some of the older writers have advocated, 

 who in turn allied it to the Coniferse, Cactacege, &c. 



In support- of the views I have stated in regard to the genus 

 Ulodendron, I shall describe specimens of three species of 

 plants which bear Ulodendroid scars ; and as these are plenti- 

 ful at certain localities in Great Britain I have been enabled 

 to study many beautifully preserved examples. The results 

 of these investigations I now beg to lay before the readers 

 of the ' Annals.' This I especially desire to do, as it explains 

 more fully than could be done, without the aid of figures, the 

 views adopted in the classification of these plants in tlie 

 * Catalogue of the Palaeozoic Plants in the British Museum.' 



The three species specially to be examined are : — 



1. Lepidodendron Veltheimianum, Sternberg. 



2. Sigillaria discophora, Konig^ sp. 

 '6. Sigillaria Taylori, Carruthers, sp. 



I am sorry that it will be necessary to criticize tlie writings 

 of several friends with whose views on Ulodendron I cannot 



