TRANSACTIONS OF THK SKCTIONS. 



603 



of them four or five circles to^vards the ch-cunifereiice, and one 

 or two towards the centre, are all that is to be seen ; and it often 

 happens that the discs are cut so thin that scarcely a trace of 

 the circles remains. 



Among the fossil Coniferce a form and arrangement of discs 

 perfectly similar to what occurs in the recent true pines is often 

 to be seen. In a specimen, for example, from the coal formation 

 of Nova Scotia in America, belonging to Professor Jamieson, 

 the discs are numerous and well defined. They are arranged 

 both in single and double rows. When in double rows, they 

 are placed side by side in a horizontal direction. Their size is 

 equal to that of the discs occurring in many of the larger true 

 pines, and some of them display distinct concentric circles. A 

 similar form and arrangement of discs the author has often seen in 

 other specimens, particularly in one from Australia, and in an- 

 other from the vicinity of Whitby. In the transverse section 

 these three fossils have regular annual layers, and present with 

 great distinctness the coniferous reticulated structure. Hence 

 it appears that in several widely distant regions fossil Coni- 

 fercE occur perfectly resembling in anatomical structure the 

 recent true pines. 



With regard to the other division of the ConifercB, namely, 

 that which includes the Araucarias and Dammaras, we find in 

 the longitudinal section, parallel to the partitions extending 

 from the centre to the surface, groups of discs differing widely 

 from those occurring in the Pine division, not only in size, but 

 also in form and arrangement. In this division, which we have 

 distinguished by the name of Araucarian, the discs occur in 

 single, double, and triple rows. They are in general arranged 

 in groups, but sometimes a row may be seen quite detached 

 from all others. The number of discs in a row varies from two 

 or three to sixty or seventy, and in any one row they are gene- 

 rally equidistant and near one another. In the double and triple 

 rows the discs are never placed side by side in a horizontal di- 

 rection, but always alternate with each other; and this is a cha- 

 racter by which an Araucarian species may at once be distin- 

 guished from any one species of the pine division. When the 

 discs are placed at a certain distance from each other, they ai-e cir- 

 cular ; when in contact, the approximating sides are compressed ; 

 and when at an intermediate distance, the approximating sides 

 become rectilinear. When the discs in the double rows are at 

 a particular distance from each other, they are partly polygonal 

 and partly circular. The contiguous boundary of each consists 

 of four straight lines, and that part of the periphery next the par- 

 tition is a segment of a circle. When the discs are arranged 



