HARDWICKE'S SCIENCE-GOSSIP. 



2ij:i 



RECREATIONS IN FOSSIL BOTANY. 



ASTROMYELON AND ITS AFFINITIES. 

 By JAMES SPENCER. 



[Continued from pas^e 203.] 



my paper on 

 " Notes on Astro- 

 myelon and its 

 Root," which I 

 had the honour of 

 reading before the 

 Geological Section 

 of the British As- 

 sociation at York, 

 I described two 

 new forms of amy- 

 eloid roots, which 

 I then believed to 

 have been the 

 roots of Astromy- 

 elon. It must be 

 premised, how- 

 ever, that my 

 reasons for re- 

 garding these roots 

 as belonging to 

 Astromyelon are purely physiological, as I have not 

 yet seen the two plants in actual connection. The 

 same may be said of any other root found in thes^ 

 coal-balls. Notwithstanding the fact that hundreds 

 of stigmarian roots have been found therein, yet no 

 one has ever seen one coimected with either Sigillaria 

 or Lepidodendron, although elsewhere they have been 

 seen connected together. But there is no safer method 

 of comparing plants than by the histological investi- 

 gation of their various tissues under the microscope. 

 This is the plan adopted by Professor Williamson in 

 tracing the history of the fossil plants and their rela- 

 tion to one another. 



My new plants belong to the order of pithless roots 

 which that author has described under the name of 

 Amyelon. One of these he has named Amyelon 

 radicans, which he regards as one of the roots of 

 Asterophyllites, and as this species bears the nearest 

 'resemblance to my new forms of any of them, it will 

 be advisable to give a brief description of it. 

 No. 215.— November 1882. 



Amyelon radicans has a solid vascular axis, formed 

 of comparatively large vessels, which are arranged in 

 a radiating manner from the centre to the circum- 

 ference. These vessels are plain on their tangential 

 faces, but beautifully reticulated on their radial faces. 

 These markings form a characteristic feature of this 

 root. The bark, as is frequently the case, is rarely 

 preserved, but such portions as are met with indicate 

 that it was formed of a rather corky parenchyma. In 

 comparing this root with its parent stem, Asterophyl- 

 lites, we find that their structure is nearly analogous 

 one with the other, and that the vessels and cells of 

 the latter plant are also characterised by being highly 

 reticulated, and that these reticulations are confined 

 to the radial faces of the vessels and cells, the other 

 faces being plain, just in the same way that they are 

 in the root. 



It is from the fact of the vessels in each plant being 

 marked with the same peculiar reticulations, and on 

 the same side, the one facing the medullary rays, that 

 their affinity has been established. 



Upon comparing the structure of Astromyelon with 

 that of my new roots, I find that there is a general 

 agreement between them. The vessels and cells in 

 each are generally barred, but there is also another 

 kind of marking which is common to both roots and 

 stems, which is a sort of cross between the barred and 

 the reticulated types ; this character may be termed 

 semi-reticulated. These semi-reticulations occur at 

 uncertain intervals among the barred vessels and cells, 

 and, like the markings on the vessels of Amyelon 

 radicans, they occur only on the radial faces. One of 

 these new roots is a most peculiar one. It has a solid 

 parenchymatous axis, the cells of which are pretty 

 uniform in size, and are arranged in radiating laminae 

 in a centrifugal manner. The portions of the bark 

 which are preserved indicate that it was of firmer 

 texture than is commonly the case in such structures. 

 To this root I have given the provisional name of 

 Amyelon radiatiis. 



The most interesting feature about the other root is 



M 



