Archaeopteris is recorded from Upper Devonian rocks of the South of Ireland, Belgium, Germany, Southern Russia, Bear Island, and Ellesmere Land in the Arctic regions, Canada, Pennsylvania, and elsewhere. Many of the specimens described under different names bear a close resemblance, which in some cases probably amounts to specific identity, to A. hibernica. A. Jacksoni originally described by Dawson[1516] and more recently by Smith and White[1517] from Devonian rocks of Maine, the Canadian type A. gaspiensis Daws., and some species figured by Lesquereux[1518] from Pennsylvania, are examples of forms which present a striking similarity in habit to the Irish species. The Belgian Devonian fossils named by Crépin[1519] Palaeopteris hibernica var. minor are regarded by him as probably identical with Goeppert’s species Cyclopteris Roemeriana from the neighbourhood of Aachen. Heer recorded Archaeopteris Roemeriana from Upper Devonian beds in Bear Island, and Nathorst[1520], who has published a more complete account of the Arctic forms, draws attention to the resemblance of some of them to A. hibernica. A species described by Schmalhausen[1521] from the Upper Devonian of Southern Russia as A. archetypus ([fig. 369], D) appears to differ from A. hibernica in the slightly less reduced lamina of the fertile segments. This species has been more adequately illustrated by Nathorst[1522] from material collected in Ellesmere Land: he is unable to confirm Schmalhausen’s statement that the pinnae are spirally disposed.

The species A. fimbriata ([fig. 369], G) described by Nathorst from Bear Island is characterised by the more deeply dissected lamina of the sterile pinnules. In A. fissilis Schmal. from Russia and Ellesmere Land the lamina ([fig. 369], E, F) is cut up into filiform segments: a fertile pinnule of this species is represented in [fig. 369], E.

Some sterile impressions figured by Krasser[1523] from Palaeozoic strata (Lower Carboniferous or Upper Devonian?) in the province of Nanshan in China as Noeggerathia acuminifissa are considered by Zeiller[1524] to be portions of an Archaeopteris or Rhacopteris frond. The resemblance to the former genus is however by no means close enough to warrant a reference to Archaeopteris. The sterile specimens described by Stur[1525] from the Culm of Altendorf as species of Archaeopteris are probably not generically identical with the Irish and Arctic species. The dichotomous branching of the rachis in A. Tschermaki and A. Dawsoni is a feature unknown in Archaeopteris. In the absence of fertile pinnae the separation of Archaeopteris from Rhacopteris is by no means easy.

Fig. 369.

  1. Archaeopteris hibernica. Fertile pinna. Dublin Geological Survey Museum. (Reduced. After Kidston.)
  2. A. hibernica. Pinnule. (Slightly enlarged. After Carruthers.)
  3. A. hibernica. Base of petiole. (Dublin Museum. After Kidston.)
  4. A. archetypus. Base of petiole: Ellesmere Land. (After Nathorst. ⅚ nat. size.)
  5. A. fissilis. Sporangia. (Slightly enlarged. After Schmalhausen.)
  6. A. fissilis. Sterile pinnule. Ellesmere Land. (Slightly enlarged. After Nathorst.)
  7. A. fimbriata. Bear Island. (After Nathorst. ⅚ nat. size.)
  8. Archaeopteris sp. Ellesmere Land. (After Nathorst. ⅚ nat. size.)

Archaeopteris was regarded by Carruthers as a fern closely allied to recent species of Hymenophyllaceae, but this conclusion was based upon an interpretation of the fertile segments which Kidston[1526] has shown to be incorrect. The latter author regarded the presence of stipules and the structure of the exannulate sporangia as evidence of a Marattiaceous alliance. In a later reference to Archaeopteris, Kidston expresses the opinion that the genus is not a true fern but a member of the Cycadofilices or Pteridosperms, a view shared by Grand’Eury[1527] and doubtless by many other palaeobotanists. The sporangia of Archaeopteris appear to be of the same type as those of Dactylotheca ([fig. 290], E, p. 399). Schmalhausen gave expression to his disagreement with Nathorst and other authors who referred Archaeopteris to the Marattiaceae by proposing the distinctive group-name Archaeopterideae.

There can be little doubt that the reproductive organs of Archaeopteris so far discovered are microsporangia, and that the plant bore seeds. The sporangia are larger than those of any known fern and, as Kidston points out, they are similar to those of Crossotheca which he has shown to be microsporangia of the Pteridosperm Lyginodendron. The presence of stipules in Archaeopteris hibernica, A. fimbriata, A. archetypus ([fig. 369], D) and probably throughout the genus does not materially affect the question of taxonomic position. Stipules are a characteristic feature of Marattiaceae and, in a reduced form, of Osmundaceae, but similar appendages are borne at the base of the petiole of the Cycad Ceratozamia. The occurrence of Aphlebiae on the rachis of Archaeopteris is a feature shared by the fronds of Neuropteris and other Pteridosperms.

Neuropteris.

The fronds for which Brongniart[1528] created this genus, though suspected by Stur in 1883 as wrongly classed among the ferns, have only recently been shown to be the leaves of Pteridosperms. As yet only one case is recorded in which