HITHERTO KNOWN AS STERNBERGIiE. 349 



Brong.,* with which plant the specimen exhibits other points 

 of afBnity, to be noticed immediately. 



Within this zone of glandular fibre or pleurenchyma is a 

 thin layer of spiral vessels, constituting a true medullary 

 sheath (figs. 5 e and 6 e). The diameter of the vessels is 

 rather less than that of the fibre, but their spiral character 

 is suflSiciently obvious to establish their nature. At the 

 inner surface of the medullary sheath there are a few verti- 

 cally elongated cells (fig. 6 /), and within these is the true 

 medulla or pith, occupying the position marked g in the 

 figures 1, 2, 5, and 6. The most striking feature of the 

 last structure, is the perfect preservation of the individual 

 cells. No recent plant could exhibit the tissue in a more 

 beautiful condition. The sections of the cells are usually 

 hexagonal ; in fig. 6 they are a little compressed vertically, 

 and exhibit a marked disposition to arrange themselves in 

 perpendicular series. In the horizontal section they appear 

 as perfect hexagons, having an average diameter of ^^ of 

 an inch, many of them being considerably larger. 



So far, the structure of this interesting fragment is that 

 of an ordinary Araucarian plant, the chief exception arising 

 fi'ora the non-existence of the annual concentric layers in 

 the woody zone ; but we now reach a point, where, so far 

 as I am familiar with the structure of the recent coniferaa, 

 this resemblance ceases. Within the true medulla, we find 

 the curious cylinder h in figs. 1 and 2. It is solid through- 

 out, and quite structureless ; consisting merely of granules 

 of one of the oxides of iron and a little iron pyrites, the re- 

 sult of chemical infiltration and deposition. On its exterior, 

 where it has come in contact with the inner surface of the hollow 

 medulla, it exhibits the transverse markings of a Sternbergia. 

 Here we obtain the solution of a problem which has so long 

 -perplexed the students of fossil phytology. The plant has 

 had a hollow pith, and Sternbergia approximata is merely the 



* Pinites Brandling!, Witham. Internal Structure of Fossil Vegetables, 

 Edinburgh, 1833. 



