100 CYCADEAE, MEDULLOSEAE. 



Breslau. Between the leaf-scars are seen broad spaces filled with the 

 transverse sections of paleaceous scales; the whorls indicated in Goppert's 1 

 figure belong to the fertile lateral shoots. Both characters are shown still 

 more plainly in the figure of R. Reich enbachiana 2 , in the museum at 

 Dresden, which was discovered in the year 1753 in a bog at Lednice near 

 Wieliczka ; I also believe that I can recognise them in the photographic 

 representation of R. Cocchiana 3 . 



A small silicified stem has been found in the Rothliegende of 

 Autun, but with its surface unfortunately not preserved, which ac- 

 cording to Renault 4 shows a structure directly allied to that of living 

 Cycadeae. This form, Cycadeoxylon Fremyi, has a pith of moderate 

 dimension surrounded by several rings of secondary growth (Renault's 

 figure 5 gives two complete rings and one half ring interposed between 

 them). These rings exhibit the features which are characteristic of Cyca- 

 deae. The wedges of wood are very slightly developed, being usually 

 only two cells in breadth, and appear in the tangential section as repeatedly 

 curved plates with enormously broad parenchymatous medullary rays running 

 between them. The vascular bundles of the medullary sheath are no more 

 to be seen here than in living stems of Cycadeae; they were probably 

 destroyed at an early period by the great development of the medullary 

 rays. But while in living forms, which show repeated formation of cambium, 

 the successive secondary growths touch one another, they are separated in 

 Cycadeoxylon by broad masses of parenchyma, which have been partly 

 destroyed ; the portions of secondary cambium must therefore have been 

 formed in the middle of the cortical parenchyma and not on its inner 

 margin. The tangential section of the rings of wood looks as if it had 

 been taken from a stem of Cycas. The pits, which occur only on the 

 radial walls of the tracheides, are in alternate rows and are polygonal from 

 mutual contact, and have exactly the appearance of Araucaroxylon. A 

 number of dark dots appear in the cortical parenchyma outside the outer- 

 most ring of secondary growth, and answer according to Renault to so 

 many gum-passages. 



We have still to consider the Medullosae, a series of remains of stems 

 from the Upper Coal-measures and the Rothliegende. The surface of these 

 stems unfortunately is known only in a few cases, and in these only im- 

 perfectly; but in their anatomical structure they show many points of 

 resemblance to the Cycadeae, though they depart from them according to 

 the most recent investigations in some important particulars. I have been 

 able to satisfy myself from preparations that these differences have been 

 correctly observed. Good figures of sections of stems of Medullosa are to 



1 Goppert (9), t. 7, f. i. 3 Goppert (9\ tt. 8, 9. 3 Caruel (1). * Renault (1), vol. i. 

 5 Renault (1), vol. i, t. 14, f. 9. 



