XI] STKOBILUS. 401 



d. Cones. 



The history of the recognition of the cones of Sphenophyllum 

 has already been briefly alluded to in chapter V., p. 100. The 

 main points in the structure of the cones of this genus were 

 known for several years, before the fact was established that 

 they belonged to Sphenophyllum stems. In 1871 Williamson^ 

 published an account of an imperfect fossil strobilus from the 

 Lower Coal-Measures of Oldham, Lancashire, under the name of 

 Volkmannia Dawsoni. The generic term Volkmannia has been 

 used by different writers for cones varying considerably in 

 structural features ; in the case of Williamson's fossil, Weiss'" 

 substituted the name Bowmanites, a genus instituted by Binney^ 

 for a strobilus apparently of the same type as Volkmannia 

 Dawsoni. In 1891 Williamson^ described some additional speci- 

 mens of Bowmanites Dawsoni, and, as in his earlier paper, he 

 compared the strobilus with Asterophyllites and Sphenophyllum, 

 but it was still a matter of speculation as to what was the form 

 of the vegetative branches. Soon after the more complete 

 account of the English cones was published, Zeiller^ recognised 

 a close agreement between some French and Belgian specimens 

 of Sphenophyllum strobili and the strobilus described by William- 

 son. A closer comparison thoroughly established the connection 

 between Bowmanites Dawsoni and Sphenophyllum ; and there is 

 little doubt that this strobilus belongs to the stem known as 

 Sphenophyllum cuneifolium (Stemb.) — a well-known species of 

 the genus. 



The most important morphological features of the strobilus 

 of Sphenophyllum may best be illustrated by a detailed account 

 of one specific type, and by a brief reference to other forms which 

 are characterised by certain differences in the number and attach- 

 ment of the sporangia. When we know that a given strobilus 

 must have grown on a Sphenophyllum stem, the obvious name 

 to assign to it would seem to be that of the plant which bore it ; 

 but there are advantages in making use of special generic terms 

 for detached cones, which cannot be referred with certainty to a 



1 WilUamson (Tl^). = Weiss (84), p. 200. •* Binhey (71). 



•* Williamson (91=). ' Zeiller (93). 



s. 26 



