[SIR J. W.DAWSON] ON THE GENUS LEPIDOPHLOIOS 67 



"I would remark here that the leafy branches in tigure 8 (phite 22) 

 are not a ' restoration,' but taken from a sketch in my note-book of a 

 specimen exposed on a large slab of sandstone. It is the more necessary 

 to remark this, as several European paleobotanists have borrowed similar 

 figures from my papers without acknowledgment, and have printed 

 them as ' restorations.' It may also be remarked that though the leaf- 

 bases of L. Cliftonense are smaller in the older part of the stem than 

 those of JJ. Murrayanum, this difference may be more apparent than real, 

 since the specimen of the latter may be from the main trunk, and that of 

 the former from one of the larger branches only. 



" These plants raise several interesting points in regard to the Lepido- 

 dendra. As I have elsewhere pointed out, ' the growth in diameter of 

 stems of Lepidodendra took place in three different ways : In some, as in 

 I/. Sternberyi, the bark retains its vitality in such a manner that the leaf- 

 bases increase in size and do not become separated from each other. In 

 others, as in Z/. Veltheimianum and L. Pictoense, the leaf-bases remain 

 small and the intervening bark becomes torn in strips, leaving wide 

 gashes without any scars. An intermediate type is that which we have 

 in Ij. rimosum and i. corriKjatuin, in which the scars increase only 

 slightly in size and then become separated by rims of slightl}" wrinkled 

 bark. It would appear, from the observations of Williamson and others, 

 that the first condition appertains to those Lepidodendra that possess 

 only a very slight development of the woody axis, while the second 

 occurs in those species in which the woody zone becomes thick and 

 strong. 



"The two species above referred to evidently belong to the first cate- 

 gory ; and, as the stems found are not large, still older stems would 

 probably show larger leaf-bases. Such species of Lepidodendra approach 

 nearer than others to the genus Lepidophloios in the expansion of the old 

 leaf-bases and the small development of the woody axis ; and it is inter- 

 esting to notice that they also resemble them in the gi-eat length of the 

 leaves and the thickness of the branches. The Lepidodendra whose 

 branches end in slender sprays are usually, if not always, those in which 

 the woody axis is large and the bark of the old stems torn and wrinkled. 



" I may add that these ditierences are most important in the discrim- 

 ination of species of the genus Lepidodendron by the markings on the 

 stems, though they have been too often overlooked. 



"Another noteworthy point is the manner in which the fruit of L. 

 Cliftonense is borne on slender branchlets with few and short leaves, ex- 

 tending from the thick branches. Such branchlets might, if alone, be 

 readily mistaken for branches of other species. They also help to explain 

 the scars of fructification often found on Lepidodendra, as well as on the 

 so-called Ulodendra, some of which, however, are not generically distinct 



1 Ibid, p. 162 ; also Acadian Geology, 1878, p. 452. 



