188 LYCOPODITES, PTILOPHYTON, PSILOTITES, 



whorls. The longitudinal section teaches us that the leaf-circles must have 

 been separated from one another by only short internodes. It is peculiar, 

 that reticulately thickened tracheides are found in Lycopodium Renaultii, 

 and tracheides with several rows of bordered pits polygonally flattened 

 by mutual pressure in L. punctatum, while in recent species scalariform 

 tracheides are the prevailing form ; but Renault states that he has observed 

 pitting of a similar kind in several living species. As I have been unable to 

 procure the only species, L. pachystachyum, cited in proof of this state- 

 ment, I have been unable to verify it. We feel here very disagreeably our 

 want of knowledge of the inner structure of Lycopodiaceae. Fibre-strands 

 are developed in the cortex of L. Renaultii, and are wanting in the other 

 species ; in these the transverse sections of roots with normal pentarch 

 bundles are seen in the middle of the cortical parenchyma. This feature 

 reminds us strongly of living Lycopodiae, in which it was discovered by 

 Brongniart l at the base of the stem and illustrated by excellent figures. 



It may be probable that Unger's 2 Arctopodium from the Cypridinae- 

 slates of Saalfeld belongs to our present group, as its author supposes. 

 Unfortunately the ill-preserved remains are known only in transverse 

 sections, which show in the centre of the stem a group of vascular bands 

 vividly recalling our Lycopodiae. These bands are radially disposed in 

 Arctopodium radiatum 3 , variously twisted, curved and branched in A. 

 insigne 4 . The cortex is destroyed in both cases and nothing can be seen 

 of the leaf-bundles. On the other hand, the specimen described by Unger 

 at the same place under the name of Cladoxylon mirabile r> is quite doubtful. 

 Here the vascular plates, if such they are, unite in the middle into an 

 irregular mesh-work ; but I have satisfied myself by examination of an 

 original preparation in the Jermyn Street Museum in London of the hope- 

 lessly bad state of preservation of this fossil. Only the discovery of fresh 

 specimens will give us the needful certainty respecting it. Such specimens 

 are said by Dawson c to be already in our possession from the Upper 

 Devonian beds of N. America (Styliola limestone), but we have at present 

 only superficial descriptions of them. Unger would unite another form of 

 this genus of his, Cladoxylon dubium 7 , with Sphenopteris refracta which 

 was noticed above on p. 164, and it cannot be denied that there is a certain 

 resemblance between them. The genus Asteropteris, Daws, has been 

 already discussed on p. 1 73 in connection with Asterochlaena. Its central 

 star-shaped vascular bundle, but especially the regular simple ring of 

 emerging leaf-bundles, may in this case also lead us to suspect that the 

 genus would more rightly find its place here among plants resembling 



1 Brongniart (1), vol. ii, t. 8. 2 Unger (5). 3 Unger (5), t. 12, f. 4. * Unger (5), t. 12, 

 ff. i, 2. s Unger (5), t. 12, ff. 6, 7. * Dawson (1,, vol. ii, p. 126. ' Unger (5), t. to, f. u. 



