ioo STUDIES IN FOSSIL BOTANY 



those of the French observer, which are preserved in 

 the form of impressions, give an excellent idea of the 

 external characters, and afford the proof that these 

 cones were really borne on Sphenophyllum stems. It 

 appears that under the type- name Sphenophyllum 

 Dawsoni two forms are included, the larger of which 

 is probably identical, as M. Zeiller believed, with 5. 

 cuneifolium, while the smaller may represent the 

 fructification of S. plurifoliatum ( = S. myriophyllum ?). 

 The following description applies, except when other- 

 wise stated, to the larger species, which may be distin- 

 guished provisionally as the a form. 



In external aspect, the cones, which reach a length 

 of several inches, with a diameter of half an inch or 

 more, are not unlike some of the Calamarian fructifica- 

 tions (see Fig. 35). The free surface of the cone is 

 formed by the upturned tips of the whorled bracts. The 

 arrangement of the organs, as shown in Sphenophyllum 

 Dawsoni, and illustrated by the diagram, Fig. 41, A, is 

 as follows : the cone has an axis 2-3 mm. in diameter, 

 bearing at intervals numerous whorls of bracts ; the 

 bracts of each verticil are coherent for a considerable 

 distance from the axis, forming a kind of cup ; at the" 

 edge of the cup, the individual bracts become free from 

 one another and turn vertically upwards, extending for a 

 distance equal to several internodes, so that the tips of 

 several successive verticils overlap each other (cf. Figs. 

 41, A, and 42). The number of bracts in each whorl 

 varies, ranging from fourteen to about twenty in the 



undescribed Verticillate Strobilus, etc.," Manchester Lit. and Phil. Soc. 

 1871 ; "Organisation of Fossil Plants of the Coal-measures," Parts v. 

 (1874) and xviii. (1891) ; Williamson and Scott, I.e. 



