SIGILLARIA 215 



of course, the small branches, rather than the great 

 trunks, are likely, as a rule, to have been preserved in 

 the petrified condition. 



The first specimen of a Sigillaria showing anatomical 

 structure was described by Brongniart, 1 as long ago as 

 the year 1839, ana " has played a most important part 

 in the history of fossil botany. The fragment was 

 about 4 cm. in diameter, and about 2 cm. long, and 

 showed a portion of the external surface with its leaf- 

 scars, as well as the internal anatomy (see Fig. 89). 

 The superficial characters have rendered it possible to 

 identify the specimen as belonging to the form Sigillaria 

 Menardi, one of the Clathraria group. 2 The parts in 

 which the structure is preserved consist essentially of 

 the wood and a portion of the outer cortex ; the pith 

 and the inner region of the cortex have perished (see 

 Fig. 89). Fortunately, however, the parts which remain 

 are the most important, as Brongniart pointed out. His 

 whole description, though nearly seventy years old, might 

 still serve as a model for such investigations. The ring 

 of wood is complete, and has a diameter of about 1 6 mm. 

 The pith was of large size, for the woody zone is only 

 about a millimetre in thickness. It consists of a large 

 number (between forty and fifty) of vascular bundles, 

 each of which is made up of an inner or primary and 

 an outer or secondary portion. The primary strands 

 are distinct from each other, though close together, and 

 are crescent-shaped, as seen in transverse section, with 



1 " Observations sur la structure interieure du Sigillaria elegans,'' 

 Archives du museum dhist. nat. vol. i. 1839. 



2 Brongniart himself referred the specimen to the Favularian species, 

 5. elegans, but this determination was subsequently corrected by Zeiller 

 and Renault. 



