Dr Halle[734] recently published an account of some imperfect leaves and stem-fragments from the Rhaetic of Scania which he named Phyllotenia (?) hadroclada, the generic name provisionally adopted having been proposed by Salfeld[735] for some rather obscure remains from the Corallian of Germany. It appears to have escaped the notice of both authors that Saporta[736] in 1894 had adopted the designation Phyllotenia for some examples of broad parallel-veined leaves from Lower Cretaceous rocks in Portugal very similar to Velenovský’s Krammera mirabilis[737]. Some other generic name must therefore be used. For the Rhaetic species the name Pelourdea would seem appropriate. The type-specimen consists of an axis 10–12 mm. in diameter with spirally disposed transversely elongated leaf-scars bearing sessile linear leaves similar to Poa-Cordaites; none of them are complete, the largest is 6 cm. long and 5–7 mm. broad with 8–12 parallel veins. An examination of the original specimens in the Stockholm Museum satisfied me that Dr Halle is justified in the opinion that they may be fragments of some Cordaitalean plant and that he was well advised to avoid the use of the name Cordaites. Salfeld’s species, Phyllotenia longifolia, may be an imperfectly preserved example of Phoenicopsis[738], but the material is too incomplete to be identified with any degree of confidence.
The Triassic leaves from Switzerland described by Heer[739], and more recently by Leuthardt[740], as Bambusium Imhofi, were referred by Fliche[741] to the genus Cordaites. The lamina is ensiform, 25 cm. long with a maximum breadth of 2·4 cm. Leuthardt’s photograph of aerial stems and rhizomes of this supposed Monocotyledon are far from convincing.
The leaves from the Lower Keuper of Thuringia assigned by Compter[742] to Cordaites without adequate evidence resemble those of P. vogesiaca, but there is no evidence as to their manner of attachment; they are 30–40 cm. long and from 1·5 to 2 cm. broad.
This species was first described by Phillips[743] from the Middle Jurassic Stonesfield Slate and afterwards referred to Zamites[744]: the leaves bear a striking resemblance to foliage of the type Cordaites borassifolius; the lamina is 30 cm. long and attains a breadth of 3 cm., the apex is acuminate and slightly contracted towards the broad concave base. My former comparison of these Stonesfield leaves with the long pinnae of Ceratozamia mexicana seemed to be supported by Phillips’s type-specimen of Palaeozamia longifolia. It may be that the supposed pinnae in Phillips’s type are spirally disposed leaves: if this is the case the specimen may be a fragment of a Podozamites; its specific identity with the larger detached specimens, though probable, cannot be demonstrated. Some leaves figured by Zigno[745] from Jurassic rocks of Italy as Yuccites Schimperianus may be identical with P. megaphylla.
The generic name Krammera, suggested by Corda, was employed by Velenovský[746] for large Cordaites-like leaves from the Lower Cretaceous of Bohemia, for casts of cones regarded by him as stems, and for fruit-like bodies. The leaves, previously described as Flabellaria chamaeropifolia Goepp., Dammara albens Presl, etc., bear a close resemblance to the large broadly linear leaves of Cordaites; the lamina reaches a length of 40 cm. and between the veins occur 1–4 finer striations. The fossils identified by Velenovský as stems bearing crowded imbricate scales, which he regarded as the persistent bases of Krammera leaves, are probably cones; they agree very closely in size and shape, also in the form of the scales, with cones of Agathis and some other recent Conifers. As the designation Krammera was instituted primarily for cones and not leaves the name Pelourdea is substituted for it.
The generic name Niponophyllum[747] was proposed for some petrified specimens of leaves or possibly leaflets from Upper Cretaceous beds in Japan which, though not definitely assigned to a group or family, are considered by the authors of the genus ‘to lie [anatomically] somewhere between Cordaites and Cycadeoidea’ ‘with a closer similarity to the former than to the latter if we compare the whole Cordaites leaf with our blade.’ The data on which this conclusion is based are, however, insufficient to justify a reference of Niponophyllum to the Cordaitales or indeed to lend any substantial support to the opinion that the Japanese specimens are anatomically more akin to Cordaites than to other plants. The type-species is represented by two specimens of leaf-fragments about 0·4 mm. thick and from 6 to 9 mm. broad containing from 21 to 33 vascular bundles; the upper part of the mesophyll is composed of palisade tissue and the stomata appear to be confined to the lower epidermis. Each bundle is accompanied by an I-shaped girder, and small patches of sclerenchyma occur next the upper epidermis between the girders; there are no resin-canals: the vascular bundles are collateral, the xylem is said to be almost entirely centripetal and exarch, but in the absence of evidence afforded by longitudinal sections the details of structure cannot be definitely determined. A comparison is made with Cycadean leaves and with leaves of Araucarineae and Podocarpeae, also with Cordaites; another type with which Niponophyllum may be compared is Desmiophyllum Solmsi[748].
The genus is interesting as an example of a petrified gymnospermous type of leaf characterised by the absence of resin-ducts and transfusion-tracheids, the possession of collateral, apparently exarch, bundles enclosed in a double sheath; but the data supplied are insufficient to enable us to allocate the specimens to a position within the class.
A specimen described by Schenk[749] as Eolirion primigenium from Lower Cretaceous beds in the Carpathian mountains closely resembles in habit a foliage-shoot of Poa-Cordaites; the leaves are narrow and linear with obtuse apices and attached, apparently, in a close spiral. Schenk assigns the plant to the Monocotyledons, but its systematic position must be left unsettled.
The list of Mesozoic specimens resembling Cordaites leaves might be extended. Apart from some Triassic and Rhaetic examples which may well be Cordaitalean, there are many others which, though similar in form and venation to Cordaites, are in all probability more closely related to Agathis and other genera; the species Dammarites Bayeri recently described by Zeiller[750] from the Upper Cretaceous of Bulgaria is a case in point. The Araucarian character of the wood of Cordaites precludes any satisfactory discrimination between Mesozoic Araucarian stems and those of Cordaitalean species, at least in the case of such material as is usually available.
Titanophyllum Grand’Euryi Renault. The remarkable leaves on which this genus and species are founded[751] were discovered in the Commentry coalfield; they occur as detached specimens and cannot be correlated with any known stem. Renault suggests that the Autun stems referred to Colpoxylon may have borne the Titanophyllum leaves, but this correlation rests only on the dimensions of the stems and the occurrence of transversely elongated scars on the surface. The lamina is thick and coriaceous, 70–75 cm. long and 20–25 cm. in breadth; the veins are parallel but not branched; numerous longitudinal striations on the upper surface indicate the presence of hypodermal stereome-strands; stomata are abundant on the lower surface and the more or less rectangular cells in the neighbourhood of the stomata appear to be papillose (fig. 485, A, B). The distal region of the lamina is often torn into strips (fig. 485, A); the approximately rectangular leaf has a broad elliptical base 9–10 × 3–4 cm.
Dr White[752] describes a specimen from the Lower Coal Measures of Missouri as ? Titanophyllum Brittsii which he speaks of as the thick base of a leaf similar to that described by Renault but, as White says, no formal diagnosis is possible without more satisfactory material. Such evidence as is available suggests that Titanophyllum is a type of Cordaitalean leaf probably closely allied to Cordaites.