Recent and Fossil Coniferce. 147 



rise to an appearance resembling that of a very acute letter V 

 placed in a horizontal position thus > . In many places the 

 lines are quite parallel. In the concentric section of Taxus bao- 

 cata, the partitions of the vessels occasionally present lenticular 

 expansions, in which there are two, three, or four subelliptical 

 openings, somewhat resembling those in the darker part of Taxo- 

 dium disticha. The appearances presented by the different sec- 

 tions of Taxus baccata are figured in the under part of Plate 

 II. 



The Salisburia adiantifolia, which differs so widely in the 

 form of its leaves from any of the pines, also presents some dif- 

 ferences in the structure of its wood. The annual layers are 

 not so distinctly defined in their boundaries as in most of the 

 pines, and, though the general form of the meshes is quadran- 

 gular, yet they are often very irregular and of different sizes. 

 In the longitudinal sections, the vessels, though varying a little 

 in width, are more rectilinear than in most of the pines, they 

 seldom or never running into each other. The discs do not oc- 

 cur so much in patches as in most of the pines, they being more 

 extensively and uniformly distributed. In the small piece of 

 wood I had to operate on, they occurred in single rows only. 

 The partitions of both longitudinal sections, present the]_fibrous 

 structure very distinctly, and in those of the concentric section 

 numerous short expansions occur, seldom containing more than 

 two openings. I could have wished to present engravings of the 

 sections of this wood, but there bas not been time to get the 

 drawings ready. 



When proper sections of the Araucariae are duly examined, 

 we find appearances which differ even more widely than those of 

 the Salisburia from the rest of the Coniferae. The want of regular 

 annual layers is a sufficient characteristic distinction in the trans- 

 verse section, and the form and arrangement of the discs is 

 equally distinctive in a longitudinal section. In the longitudinal 

 section of the Araucarias, parallel to a radius, groups of discs, ar- 

 ranged both in single and double rows, are often to be seen. 

 In sonie parts the groups are more numerous than in others, 

 and a solitary row, consisting of a few discs only, may often be 

 seen where no groups occur. There is a peculiarity in the 

 single rows of discs which alone would distinguish the Arauca- 



k2 



