LEAVES AND CONES IN VERTICAL ROWS. 357 



ton, Bothrodendron, Ulodendron.* Our figures PI. 56, 

 Figs. 3, 4, 5, 6, represent portions of the trunk and scars 

 of some of these extraordinary Coniferoe. 



Among existing vegetables, there are only a few succulent 

 plants v^^hich present a similar disposition of leaves, one 

 exactly above another in parallel rows ; but in the fossil 

 Flora of the Coal formation, nearly one-half, out of eighty 

 known species of Arborescent plants, have their leaves 

 growing in parallel series. The remaining half are Lepido- 



* The genera composing this group are thus described, Foss, Flora, vol. 

 ii. p. 96. 



7. Sigillaria. Stem furrowed. Scars of leaves small, round, much nar- 

 rower than the ridges of the stem. See Pi. 56, Figs. 1, 2, 2'. 



2. Favularia. Stem furrowed. Scars of leaves small, square, as broad as 

 the ridges of the stem. See PI. 56, Fig. 7. 



3. Megaphyton. Stem not furrowed, dotted. Scars of leaves very large, 

 of a horse-shoe figure, much narrower than the ridges. 



4. Bothrodendron. Stem not furrowed, covered with dots. Scars of cones, 

 obliquely oval. 



5. Ulodendron. Stem not furrowed, covered with rJiomboidal marks. 

 Scars of cones circular. See PI. 56, Figs. 3, 4,5, 6, 6'. 



In the first three genera of this group, the scars appear to have given 

 origin to leaves; in the latter two they indicate the insertion of large cones. 



In the genus Favuluria (PI. 56, Fig. 7) the trunk was entirely covered 

 ■with a mass of densely imbricated foliage, the bases of the leaves are nearh' 

 square, and the rows of leaves separated by intermediate grooves ; whilst in 

 Sigillaria the leaves were placed more loosely, and at various intervals in 

 various species. (Foss. Flora, PI. 73. 74. 75.) 



In the genus Megaphyton the stem is not furrowed, and the leaf scars arc 

 very large, and resemble the form of horse-shoes disposed in two vertical 

 rows, one on each side of the trunk. The minor impressions resembling 

 horse-shoes, in the middle of these scars, appear to indicate the figure of the 

 woody system of the leafstalk. (Foss. Flora, PI. 116, 117.) 



In the genus Bothrodendron (Foss. Flora, IM. 80, 81) and the genus Ulo- 

 dendron, (Foss. Flora, PI. 5. 6.) the stems arc marked with deep oval or cir- 

 cular concavities, which appear to have been made by the bases of large 

 cones. These cavities are ranged in two vertical rows, on opposite sides 

 of the trunk, and in some species are nearly five inches in diameter. (PI. 

 56. Figs. 3. 4. 5. 6.) 



