SIGILLARIA 2i 9 



some specimens of another Sigillaria showing internal 

 structure ; 1 the superficial characters of the stem 

 enabled them to identify it as belonging to the 

 Leiodermarian form 5. spinulosa ; the latter, however, 

 as mentioned above, is now known to have been 

 identical with the Clathrarian S. Brardi, so there is no 

 important distinction, so far as external characters are 

 concerned, between Renault's and Brongniart's species. 

 Some authors, indeed, have even united *S. Menardi 

 with S. Brardi, in which case the two French observers 

 would have been dealing merely with varieties of the 

 same species. The anatomy, however, appears to 

 negative this view ; the two species are probably 

 distinct, though nearly allied. 



In the case of .S. spinulosa several specimens were 

 available for investigation, from branches of various 

 sizes. The primary wood is of about the same thick- 

 ness as in the former species, but shows curious 

 variations in its arrangement. At some points it is 

 broken up into distinct bundles, quite similar to those 

 of 5. Menardi (see Fig. 91), but elsewhere, even in the 

 same transverse section, it forms a continuous band for 

 a considerable distance (see Fig. 90). 2 We thus see 

 that the separation of the primary xylem-zone into 

 definite strands is not necessarily a character of any 

 taxonomic importance. The primary wood was centri- 

 petal, and agrees in minute structure with that of 

 5. Menardi. The secondary zone (which in some of 



1 " £tude du Sigillaria spinulosa" Mint. pris. par divers savants a 

 I ' Acadimie des Sciences, tome xxii. 1875. 



2 For the photographs reproduced in these two figures I have to thank 

 my friend Mr. Kidston, who took them from sections of one of the 

 original specimens. 



