Recent and Fossil Coniferce.. 139 



near the pith than towards the surface, but, in certain species, 

 as Pinus Larix, Juniperus communis, &c., even when the stem 

 is nearly cylindrical, the breadth of some layers is many times 

 greater on one side of the tree than it is on the opposite side. 

 It sometimes happens, too, that a layer of considerable breadth 

 on one side becomes so narrow on the other side as entirely to 

 vanish, and some layers frequently assume very different breadths 

 in different parts of their circuit. The Juniperus communis 

 often presents these undulations in an elegant manner. 



The annual layers of the Coniferae, wherever they occur, are 

 always separated from each other by distinct lines of demarca- 

 tion, and, as far as my observations have extended, they occur 

 in all the true pines, yews, junipers, cypresses, and thuja? ; 

 but, in the tribe of Araucarias, they are entirely wanting. I 

 have seen, it is true, only two of the four known species of Arau- 

 caria, namely, the Braziliana and Cunninghami. These have 

 certainly no distinct annual layers, and it is highly probable that 

 the same character extends to the other two species. The Bra- 

 zilian specimen in my possession, which grew in this country, is 

 a portion of a very young stem ; but the section of the other, for 

 which I am indebted to the kindness of Dr Greville, is from 

 Moreton Bay in New Holland, and is nearly fourteen inches in 

 diameter. Irregular zones, displaying a slight diversity of co- 

 lour, are to be seen throughout the whole surface, but there is no 

 appearance of the distinct bounding lines that characterise the 

 annual layers of all the other tribes of Coniferae. As I have had 

 no opportunity of examining either of the two species of Dam- 

 mara, I am unable to say whether they have annual layers or 

 not. I shall, therefore, not indulge in conjecture, but express 

 a wish that attention may be given to the want of annual layers 

 in the tribe of Araucaria, as it will enable us to explain why an- 

 nual layers are not to be seen in some fossil Coniferae. 



Besides the want of annual layers, there are other distinguish, 

 ing characters to be seen in the Araucariae, to which I shall 

 presently have occasion to allude, and, with regard to the annual 

 layers, it may be right to subjoin that they occur in pines grow- 

 ing in the warm as well as in the temperate regions, I have 

 seen them in various species from the East Indies, as in the long- 



