STIGMARIA. 



many other transverse sections which have been studied is the only probable 

 argument which can be advanced. But since we find great numbers of 

 detached appendages which inclose a bundle endowed with secondary 

 growth, there remains only one of two alternatives ; either growth in thick- 

 ness reappeared in these appendages, or the trace in them passed through 

 the basal diaphragm in another form than that of the specimen hitherto 

 studied, namely, with retention of the secondary wood. Should the latter 

 be the right conclusion, we should then be obliged to assume that there 

 were distinct species of Stigmaria differing from one another in this respect. 

 Renault indeed states that he has seen very different forms of trace at the 

 same time on one and the same axis, but his arguments in proof of this, 

 which we must notice again presently, are not to my mind conclusive. Nor 

 can the facts as here given be reconciled without forced interpretations 

 with Williamson's 1 view, who sees in the different trace-types only the 

 pictures of different portions of one and the same organ of the same plant. 

 These are just the questions in which the anatomy of the parts is not a 

 decisive guide in any direction. There are no successive sections, as far as 

 I know, of appendages still attached to manifest axes of Stigmaria; but 

 these alone can clear up the questions which we have been considering. 



Many very different accounts have been given in the course of time 

 both of the position of Stigmariae in the system and of their morphological 

 differentiation. Opinion has been more divided on these points than in the 

 case of any other fossil vegetable remains, and no full and certain deter- 

 mination of them has been obtained up to this day in spite of the almost 

 overwhelming literature. In proceeding to review the efforts which have 

 been made to effect this purpose, we may very well avoid any lengthy con- 

 sideration of the comparisons proposed by earlier authors with Opuntiae, 

 Cacaliae, Ficoideae, Stapeliae, Aroideae, and even with Palms. A sum- 

 mary notice of them will be found in Goppert 2 . 



The first person who suggested, though on weak grounds, a close con- 

 nection of our remains with Lycopodinae, and especially with Isoetes, was 

 Brongniart 3 . His idea, which did not at first meet with much approval, 

 won its way in time to recognition when better arguments could be adduced 

 in its support, and may now be said to be very generally accepted. The 

 first distinct, and for some time the standard, account of the structure of 

 these plants was communicated by Lindley and Hutton 4 , and was founded 

 on the branched specimen discovered in the roof of the Bensham seam in 

 Jarrow mine, and figured by them. This specimen, which being fixed 

 in the roof can be seen only from below, shows twelve well-preserved in 

 some cases dichotomously divided Stigmaria-branches, which even have the 



1 Williamson (5), p. 350. 2 Goppert (20), also (1) and (3). 3 Brongniart (4), p. 82. 



4 Lindley and Hutton (1), vol. i, t. 31. 



