. Le Eusporangiatae ; la morphologie comparative des Ophioglossaceae et Marattiaceae. Ophioglossaceae ; Marattiaceae. 176 LES MARATTIALES ou plus, est debout, les feuilles étant qu'ils sont disposés en spirales dans Marattia et Angiopteris. Les pétioles de cette espèce sont caractérisées par des élargissements curieux ou noeuds, ce qui peut se produire dans les autres espèces, mais également sont beaucoup moins mis en évidence. Les feuilles de D. elliptica atteignent une longueur d'environ 50 centimètres et les brochures, qui sont beaucoup plus grands que ceux des autres espèces, sont moins nombreux, puisqu'il n'y a habituellement environ onze ans. L'endroit bien n

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. The Eusporangiatae; the comparative morphology of the Ophioglossaceae and Marattiaceae. Ophioglossaceae; Marattiaceae. 176 THE MARATTIALES or more, is upright, the leaves being spirally arranged as they are in Marattia and Angiopteris. The petioles in this species are characterized by curious enlargements or nodes, which may occur in the other species also, but are much less prominent. The leaves of D. elliptica reach a length of about 50 centimeters and the leaflets, which are much larger than those in the other species, are less numerous, there being usually about eleven. The conspicuous nodose swellings seen in the petiole are repeated on a smaller scale in the rachis at the base of each pair of leaflets. Sections of the stems were examined in D. jamaicensis and D. elliptica, which, except for a diflFerence in size, agree closely in their structure. The ground tissue, as was first pointed out by Kiihn, consists entirely of parenchyma, through which are scattered many conspicuous tannin sacs which, in preserved material, appear to the naked eye as numerous black specks. The section of the vascular cylinder looks very much like that of the younger sporophytes already described, but the number of bundles seen in the section is larger, and there is a group of several bundles instead of the single medullary strand seen in the section of the younger stem. In a section from a large specimen of D. elliptica in which the rhizome, including the old leaf bases.. Fig. 160. A. Section of petiole of fourtli leaf of Damea jamaicetuis. X40. B. Leaf trace. C. Bundle of petiole. X180. was about 3 centimeters in diameter, the outer ring of bundles contained thirteen, while within this was a smaller circle composed of five medullary bundles, three large ones and two smaller ones. In a similar section of a medium-sized section of D. jamaicensis, in which the rhizome was about half the size of that in D. elliptica, there were nine bundles in the outer ring and four in the middle, tw

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