274 Contributions towards Establishing the General Character 



connecting threads of cuticle are remarkably distinct : we are thus enabled 

 to trace the spiral of this specimen in the direction of the leaf-bases a, a. 

 Guided by this circumstance, and notwithstantling the obvious con- 

 nection existing between the leaf-bases h, b, in the specimen represented 

 in figure 2, I am inclined to think that the spiral of this Lepidodendron 

 coils in the direction of the leaf-bases a, a. I am strongly supported in 

 this view, from having observed on several specimens^ that the lozenge, 

 corresponding to the one marked c of the adjoining spiral on the left, is 

 below that marked d of the spiral on the right, and not the converse 

 (vide e,/), as would be the case were the spiral to take in the lozenges 

 b, b. This will be understood by a reference to the specimen repre- 

 sented in figure 4 (PI. IV.), on which, though there are no threads of 

 cuticle visible, it is quite clear the spiral cannot have run in any other 

 direction than in that of the lozenges a, a x, because the apex of that 

 which is marked a, is above the inferior part of those marked b and c. 

 We are thus enabled to see that the intervening lozenges b and c, are 

 situated relatively to each other as just observed. By attending to this 

 circumstance, I have been enabled to trace the direction of the spiral 

 in specimens which oflPered no other means of deciding this point.* In 

 figure 3, the lozenges (6, c, d, and e) of four spirals come in between 

 the lozenges (a, a) belonging to the spiral which unites those last par- 

 ticularised : this is certainly an extreme case, and is evidently due to an 

 unusual longitudinal development ; this is proved by what is exhibited 

 in the specimen given in figure 2, which has not increased so much in 

 this direction, and which exhibits two lozenges g and h, in addition to 

 the ordinary number, approximating to the relative position of those 

 marked d and e in figure 3. 



Having shewn a resemblance between the irregular ribs on some re- 

 cent ConifercBj and the more decided instances of this character so highly 

 characteristic of Sigillaria, I will, in the next place, endeavour to ascer- 

 tain how far the cause of those on the former can account for the produc- 

 tion of their analogues on the latter. With this view, a representation 

 is given in figure 5 (PI. IV.), twice their natural size, of the leaf-bases 

 of that beautiful Nepaul pine — Abies Webhiana, a fine individual of which 

 is now growing on the grounds of Sir Charles Monck of Belsay. By 

 following the leaf-bases a, a, through the connecting threads of cuticle b, b, 

 it will be seen that the spiral runs to the left, and that its volutions are 

 extremely remote from each other. But the most important feature on 

 this specimen, is the very decided way in which it is ribbed, so much so, 

 as to appear like a miniature Sigillaria, On the larch, the leaf-bases 

 are connected with each other by means of threads of cuticle, which in 



♦ According to this view, scales 1, 14, 27, 40, and 53, in Professor Henslow's 

 figure of the spruce cone, follow the course of what may be termed the true spiral^ 

 — Vide" Descriptive and Physiological Botany," fig. 137, p. 127 in Lardner's Cy- 

 clopedia. 



