CARBONIFEROUS LYCOPODS AND SPHENOPHYLLS. 99 



divided ramification of Lepidodendron or Bothradendron (i.e., 

 Bothradendron minutifolium, Boulay sp.). In some cases the 

 stem consisted of a narrow conical trunk, as figured by Golden- 

 berg. 1 This stem was 18 feet in height. 2 In other cases the 

 stems of Sigillaria seem to have diminished little in girth but to 

 have possessed an upright columnar mode of growth. Of this 

 type Goldenberg has also given figures. 3 Two good Sigillarian 

 stems of this form are preserved in the Museum, Newcastle-on- 

 Tyne, and another in the Sunderland Museum. All these 

 columnar stems belong to the Rhytidolepis Section. 



In the Rhytidolepis Section the ribs increased in number as 

 the plants advanced in age. Hand specimens occasionally show 

 the interpolation of an additional rib, and such have already 

 been figured. 4 I have also specimens showing the same occur- 

 rence; but the most beautiful example with which I am 

 acquainted is a trunk in the Sunderland Museum. It shows the 

 lower portion of a stem, 6 feet 6 inches in height. It is slightly 

 bottle-shaped at the base, where it measures 5 feet in circum- 

 ference. On this part of the stem there are 29 broad ribs. 

 About two feet from the base many of these ribs divide, and 

 their number is then increased to 40, with a stem circumference 

 of 3 feet about four feet from the base. All these additional ribs 

 do not arise from a division of the primary basal ribs, but new ribs, 

 with pointed extremities, are inserted between the older ones ; thus, 

 about 6 inches below the broken-over extremity of the trunk, there 

 are 45 ribs, though the stem is considerably smaller than at the 

 base, where the number is 29. 5 A transverse section of such a 

 specimen, supposing its internal structure were preserved, would 

 show at the base a much smaller number of leaf-traces than a 

 section taken immediately below the broken-over extremity. 6 



1 Goldenberg, Flora Sarcepont. foss., PL B., fig. 13. 



2 See also Goldenberg, I.e., PL IV., fig. 1; Grand 'Eury, Geol. et 

 Paleoni. du Bassin houil. du Gard, PL XIII., figs. 7, 8, 9, 10. 1890. 



3 Goldenberg, I.e., PL X., fig. 6. 



4 Zeiller, Flore foss. Bamin houil. d. Valenciennes, PL LXXVIIL, fig. 3 

 (Sig. laevigata J ! PL LXXXV., fig. 1 (Sigillaria tesseilata J. 



5 See Goldenberg, Flora Saraepont. foss., Heft. I., pp. 26 and 37-38, PL 

 IV., fig. 1. 



6 Kidston, Trans. Boy. Soc. Edin., Vol. XXXIX., Part 1 (No. 5), pp. 

 46-47. Woodcut. 



