124 



POSSIL PLANTS. 



magnified 4 diameters ; V , V showing the medullary rays or bundles traversing the inner 

 radiating cylinder, and d' , d' those traversing the outer radiating cylinder, 



" PI. xxxiii, fig. 1, is a longitudinal section of a portion of the same specimeR, 

 exhibiting the central axis ^ and the inner radiating cylinder, magnified 15 diameters. 

 Pig. 2 shows several of the vessels of the central axis, as they would be if they were not 

 ground away in the operations of slicing and polishing, magnified 45 diameters. Pig. 3 

 is a tangential section of the inner radiating cylinder ; b showing the barred vessels, and 

 //' the medullary rays or bundles, magnified 15 diameters. Pigs. 4 and 5, longitudinal 

 and tangential sections of the same specimens, showing the structure of the outer 

 radiating cylinder ; d denoting the tubes, or elongated utricles, of which it is composed, 

 and d' the medullary rays or bundles which traverse it, magnified 10 diameters. 



" PI. xxxvi, fig. 1, represents a transverse section of a ribbed and furrowed stem 

 (' No. 3'), displaying similar cicatrices to that of 'No. 2,' given in pi. xxxi, and having a 

 like central axis, as well as like internal and external radiating cylinders and other parts, 

 magnified 2 diameters. It is given for the purpose of more distinctly showing the tubes 

 or elongated utricles, d, and th6 fusiform openings formed of very open muriform tissue, 

 d' , enclosing the medullary rays or bundles which traverse the external radiating 

 cylinder; this it does in a very marked manner; magnified 20 diameters. 



" In pi. XXXV, figs. 1, 2, and 3 (' Nos. 4, 5, and 6'), are shown the exteriors of 

 three central axes, separated from large-ribbed-and-furrowed stems, in every respect 

 similar to those described in pi. xxxi, and pi. xxxiv ; and such as might easily be taken 

 for small Calamites ; magnified 2^ diameters. Pig 4 (' No. 7') shows the outside of the 

 internal woody cylinder of a Stigmaria, with ribbed and furrowed characters, resembling 

 those shown on the outsides of the central axes lastly described ; also magnified 2| 

 diameters. The first three specimens, ' Nos. 4, 5, and 6,' are from the Halifax ' Hard 

 Seam' of coal, at South Owram; but 'No. V is from the Wigan " Pive-feet Mine," a 

 seam in the Middle Coal-measures. The tangential sections which show the medullary 

 rays, or bundles that traverse the inner and outer radiating cylinders, afford clear evidence 

 of the diff"erent appearance of the bundles marked h" in pi. xxxiii, fig. 3, from those in 

 pi. xxxiv, fig. 2, marked d' . 



" Specimens ' Nos. 2 and 3' bear considerable resemblance to the Sigillaria elegansoi 

 Brongniart, with respect to their internal radiating cylinder and the medullary rays or 

 bundles which traverse it, assuming that such vessels come from the outside of the 

 central axis, and not from the exterior of the internal radiating cylinder, as that distin- 

 guished savant supposed. Certainly there is no evidence in my specimens to support the 

 latter view. A great many specimens have been broken up and destroyed for the 



1 " In the plate the small tubes a" appear to be divided by septa. This is certainly the case in 

 one slice ; but in another of the same specimen these septa are not seen, but small barred vessels appear 

 in their places, so the former may probably be due to the direction of the slice being cut along the dark 

 line which traverses the central axis, as shown in pi. xxxii, figs. I and 2." 



