of the Fossil Plants of the genus Slgillaria. 277 



grown into the lozenges of this genus. Considering this, and associat- 

 ing it with what has been afforded by the larch and the Nepaul pine, 

 it appears to me, that the view which has been advanced is supported 

 by the strongest analogical evidences, and, of course, is so far placed 

 beyond being a mere hypothesis. 



Brongniart, in his " Vegetaux Fossiles," says, the width of the ribs of 

 Sigillaria generally remains the same, not only on various parts of the 

 same stem, but on the various individuals of the same species.* The 

 three North Biddick specimens, however, strongly oppose the general 

 application of this view, inasmuch as their ribs are clearly seen de- 

 creasing in width in the ascending direction, so much so, that they are 

 three inches wide at the base of one of the specimens, and under an 

 inch at its apex. This great disparity is confined to the stem ; but, it 

 must not be forgot, that there are evidences of these specimens having 

 been furnished with branches. Now, as a considerable decrease in the 

 width of the ribs obtains on the stem, it seems but reasonable to con- 

 clude, that a still further diminution would be continued into the 

 branches, — that, in short, there would be exhibited on the latter all the 

 characters of the so-called genus Favularia. For my part, I have little 

 or no doubt that this was the case, and I am strongly persuaded in its 

 favour, from having procured from a small space in one of the pits of 

 this neighbourhood, a great number of specimens uniting Sigillaria rent- 

 formis with Favularia tessellata (?). But, if further evidence be required 

 to destroy the general bearing of Brongniart's view, it is undoubtedly 

 afforded by the highly interesting specimen represented in Plate 15 of 

 Artis' " Antediluvian Phytology." 



The specimens just referred to as having been obtained from this dis- 

 trict, require some further notice, on account of their uniting such dis- 

 similar forms as those which have been named. If this be the case, 

 it follows, as a matter of course, that a number of species of Sigillaria 

 will fall to the ground. In saying that these specimens unite S. renifor- 

 mis and Favularia tessellata (?), it is to be understood, that I am fully per- 

 suaded such specimens belong to the same species, and even to the same 

 individuals. This is strongly corroborated by the following fact : — On 

 all the specimens, the size and form of the leaf-scars are much about the 

 same ; but there is a remarkable variation in the width of the ribs, — a 

 variation which has been produced, not by the whole rib being thus al- 

 tered, but merely those parts which are lateral to the leaf- scars. How 

 are we to account for this fact ? Simply, I would suggest, on the sup- 

 position that the attachment of the leaves to the median line of the ribs 

 has checked the horizontal extension of this part, while the furrows and 

 the lateral parts of the ribs were allowed to augment in this direction, in 

 proportion to the development of the stem. Guided by this supposition, 



♦ " Vegetaux Fossiles,'' Tome 1, p. 395. Brongniart certainly makes excep- 

 tions of dichotomous specimens ; but the North Biddick fossils have undoubt- 

 edly been branched. The exceptions, therefore, cease to be such. 



