108 



POSSIL PLANTS. 



2. WiTHAM^ (Stem) describes his Anahathra pulcherrima, found in the Mountain- 

 limestone series at AUenbank, in Berwickshire, as follows : — " A medullary axis ; woody 

 tissue consisting of elongated cellules; medullary rays scattered at great distances. 

 Stems roundish or compressed, tapering ; pith of irregular polygonal cellules ; woody 

 tissues, in the transverse section, presenting the appearance of regular, parallel, radiating 

 series of four-sided or subhexagonal cellules, with radiating tubular ducts interspersed 

 at intervals. In the longitudinal sections the cellules have all their walls very regularly 

 marked with parallel straight lines or ridges. The medullary rays, in their transverse 

 section, are of an elliptical form, and composed of irregular reticulations." 



3. LiNDLEY and Hutton" (Roots). — Describing Mr. Prestwich's specimen oi Stiffmaria, 

 they state — " The transverse section exhibited a meshing, something like that of Coniferse, 

 but with no concentric circles, and with the medullary rays consisting rather of open 

 spaces between the other tissue, than of common muriform tissue found in such places. 

 The longitudinal section (fig. 2) presented an assemblage of spiral vessels, of a very 

 tortuous and unequal figure, without any woody or cellular matter intermixed. 



" These formed a cylinder, which was surrounded externally by a mass of inorganic 

 mineral matter, upon which surface the peculiar markings of Btigmaria were preserved, 

 and which enclosed a hollow cavity, altogether destitute of mineral deposit. 



" It would therefore appear that Stipnaria was a plant with a very thick cellular 

 coating or bark, surrounding a hollow cylinder, composed exclusively of spiral vessels 

 and containing a rather thick pith ; and that the plates of cellular tissue, which preserved 

 the communication between the bark and the pith, were of so delicate an organisation 

 that they disappear under the mineralising process which fixed the organic characters of 

 the wood." 



4. Brongniart^ {Sigillaria, &c.). — "En faisant abstraction des colorations diverses 

 de la silice qui occupe les parties dans lesquelles le tissu est completement detruit, on voit 

 que cette tige est formee de deux cylindres de tissus plus resistants, et dont la texture 

 est parfaitement conservee, cylindres qui ne sont pas concentriques I'un a I'autre ; I'un, 

 tout-a-fait exterieur et superficiel, constitue une sorte d'ecorce, et presente exterieurement 

 les bases saillantes, ou mamelons rhombo'idaux, qui correspondent aux points d'insertion 

 de chaque feuille ; le tissu qui le compose, et qui parait parfaitement continu, est cellulo- 

 fibreux, tres-fin et tres-dense ; I'autre cylindre, interieur, rapproche d'un cote du cylindre 

 exterieur, en est separe par un espace assez large sur un cote, etroit de I'autre, qui parait 

 avoir ete occupe par un tissu cellulaire delicat (pi. i, figs. 3, 4, e e), dont il ne reste de 

 trace que dans quelques points, et surtout pres de la zone corticale ou exterieure ; ce 

 tissu cellulaire est represente pi. ii, figs. 1, 2, 3, e ; e, I'interieur de ce merae cylindre 

 (pi. i, figs. 3, 4, a (Z ; pi. ii, 1 a) ne presente que de la silice amorphe, transparente ou 



1 ' On the Internal Structure of Fossil Vegetables,' p. 74, Edinburgh, 1833. 



- ' Fossil Flora,' &c;, by Lindley and Hutton, vol. iii, p. 47, 1838. 



^ 'Archives du Museum d'Histoire Naturelle,' &c., tome i, p. 410, 1839. 



