XVl] SIGILLARIA 209 



found ; this may, however, be in part due to a confusion with 

 Lepidostrobi which so far as we know do not differ in important 

 respects from Sigillariostrobi'. 



There can be no doubt that Sigillaria usually produced its 

 cones on slender pedicels which bore a few leaves or bracts in 

 irregular verticils, or in short vertical series on comparatively 

 stout stems, an arrangement reminding us of the occurrence of 

 flowers on old stems of Theobroma and other recent Dicotyledons. 

 As Renault^ pointed out the fertile shoots are axillary in origin. 



Dr Kidston' is of opinion that certain species of Sigillaria 

 bore cones sessile on large vegetative shoots characterised by 

 two opposite rows of cup-like depressions like those in the 

 Ulodendron form of Lepidodendron Veltheimianum (fig. 157). 

 He has described the Ulodendron condition of two species, 

 Sigillaria discophora (Konig) and S. Taylori (Carr.) ; the cup- 

 like depressions may have a diameter of several centimetres 

 and are distinguished from those of Bothrodendron by the 

 almost central position of the umbilicus. The specimens 

 which he figures as ;S. discpphora are identified by him with 

 the stem figured by Konig as Lepidodendron discophorum and 

 by Lindley and Hutton* as Ulodendron minus. We have 

 already dealt with the nature of Ulodendron shoots, expressing 

 the opinion that in spite of the often quoted specimen described 

 by D'Arcy Thompson ^ in which a supposed cone occurs in one of 

 the cups, there is no satisfactory case of any undoubted cone 

 having been found attached to the large Ulodendron scars. It 

 is more probable that the Ulodendron depressions represent 

 the scars of branches, either elongated axes, or possibly in 

 some cases deciduous tuberous shoots which served as organs 

 of vegetative reproduction. A specimen figured by Kidston 

 as Sigillaria Taylori from the Calciferous sandstone of Scotland* 

 bears a row of slightly projecting "appendicular organs" 

 attached to a Ulodendron axis; but these furnish no proof of 

 their strobiloid nature. The main question is, are these Ulo- 

 dendron shoots correctly identified by Kidston as Sigillarian? 



1 Kidston (97). ^ Eenault (96) A. 



3 Kidston (85), * Lindley and Hutton (31) A. PI. vi. 



5 Thompson (80). " Kidston (85) PI. vi. fig. 10. 



