156 PBOCEEDINGS OF THE GEOLOGICAL SOCIETY. 



and flattened at the top, exactly as somewhat strong fistulous stems 

 would be. It is obviously impossible that casts of medullary cavities 

 could be preserved in this manner. Neither Sternhergice nor casts of 

 the pith of Calamodendra ever occur under such circumstances. 



3. The stems of Calamites may be seen to have produced leaves 

 and branchlets in such a manner as to prove that they are complete 

 stems preserving their external surface. In my paper on the South 

 Joggins, I figured and described the leaves of C. Cistii as seen 

 attached to the erect stems. I have since, in ' Acadian "Geolog^^,' 

 figured those of C. Suclcovii, found under similar circumstances ; and 

 I have specimens which appear to me to verify the figure given by 

 Lindley and Hutton of the leaves of C nodosus. I have also ob- 

 tained beautifully preserved specimens of the leaves of C. transi- 

 tionis, a species common to the Devonian and Lower Carboniferous. 

 It has been supposed that the sears on the nodes of Calamites are 

 merely the marks of bundles of vessels passing from the interior to- 

 wards the surface ; but it is obvious that, in the case of stems actually 

 producing leaves and branchlets, this cannot be the true explana- 

 tion, though after seeing the very instructive slices of Prof. William- 

 son's Calamopitus, kindly shown to me by him, I am prepared to 

 admit that in some specimens, at least, they may represent the 

 " meduUary radii," which, as already stated, sometimes appear in 

 addition to the true vascular scars. 



4. The leaves of Calamites were not, as is often stated, identical 

 Avith those of Asterojphyllites ; and the genus Calamocladus, in Avhich 

 Schimper has placed many plants of the latter genus, is therefore 

 altogether unnecessary. A careful microscopic examination of the 

 leaves which I have found attached to Calamites convinces me 

 that thej^ have distinct characters, and affords an additional link 

 of connexion with Equisetacese. The leaves of Asterojphyllites proper 

 are flat, expanded in the middle, and with a distict midrib. Those 

 of Calamites are strictly linear, thick, and angled, and are be- 

 sides marked with transverse lines or stria3. Similar transverse 

 lines occur on the branchlets of some modern Equiseta, and are 

 produced by lines of minute stomata. "Well-preserved specimens of 

 Calamite-leaves have precisely the same appearance, so that they 

 may be compared to branchlets of Equiseta deprived of their sheath. 

 Plattened leaves of Calamites, it is true, sometimes present the ap- 

 pearance of a midrib ; but this arises either from the prominence of 

 the upper angle, or the appearance of an internal axis through the 

 substance of the leaf. Unless very badly preserved, they can always 

 be distinguished from Asterojjltyllites or Anmdaria. The connexion 

 supposed, by Ettingshausen and others, to obtain between Calamites 

 and Asterophyllites has arisen either from accidental association, 

 or from failure to distinguish leaves and stems of Calamites from the 

 corresponding parts of Asterojphyllites* . The conjecture of Brong- 

 niart that some, at least, of the Asterojyhyllites may be leaves, not of 



* The species Asterophyllites comosus, L. v. IT., appears to consist of, or to in- 

 clude, leaves of Calamites; and there is reason to doubt whether the proper 

 Asterophyllites should be separated from Anmdaria. 



