Chapter XXVII (1)

GENERA OF PTERIDOSPERMS, FERNS, AND _PLANTAE
INCERTAE SEDIS._

The genera and species described in this Chapter are founded on sterile leaves or portions of leaves, and in the great majority of cases the reproductive organs are either imperfectly known or have still to be discovered. Some of the genera, the smaller number, are no doubt true ferns, while most of them may safely be regarded as plants which will ultimately be shown to belong to some other group, in most cases that of the Pteridosperms. It is possible that a few of the types may be members of the Cycadophyta rather than of the Pteridospermeae, but evidence as to systematic position is for the most part of a negative kind or too incomplete to lead to any definite expression of opinion as to the cycadean or pteridosperm nature of the imperfectly known Palaeozoic or Mesozoic species. Many of the genera are of little botanical interest, though even the most problematical are of importance as criteria of geological age. Genera which there is good reason for including in the Pteridosperms are dealt with in this section, in order that the Chapter in Volume III. devoted to this important group may be limited to more completely known types.

In most text-books it is customary to employ family names for sterile fern-like fronds which possess similar venation features or have in common certain vegetative characters, the value of which it is impossible to estimate. In the following account family or group names are not adopted, on the ground that such slight utility as they may have is more than counterbalanced by the risk attending a grouping under one name of plants which may agree only in unessential characters. The practice of classifying fossil plants has been carried to excess. Grouping together genera as a matter of convenience unavoidably creates a prejudice in favour of actual relationship, which may or may not exist.

Taeniopteris.

This generic name was instituted by Brongniart[1254] for simple linear or broadly linear leaves with a prominent midrib from which secondary veins, simple or dichotomously branched, are given off at right angles or obliquely. The frond of the type-species _Taeniopteris vittata_ (fig. 332), characteristic of Jurassic floras, was compared by Brongniart with the pinnules of _Danaea_ and _Angiopteris_. Among recent ferns the Taeniopteris form of frond and venation is represented by _Oleandra neriiformis_, _Asplenium nidus_, and many other species. Though usually applied to fronds which there is good reason for regarding as simple leaves, the generic designation _Taeniopteris_ has been extended to include pinnate fronds, e.g. the Upper Palaeozoic species _T. jejunata_ Grand’Eury, and _T. Carnoti_ Ren. and Zeill. (fig. 330, A). The compound fronds from the Lower Coal-Measures of Missouri described by Dr White[1255] as _T. missouriensis_ are characterised by decurrent and confluent Taeniopteroid pinnules. In a later reference[1256] to this plant White pertinently adds, “perhaps it belongs more properly in _Alethopteris_.”

Leaves of the _Taeniopteris_ type are described by several authors as species of _Oleandridium_, _Angiopteridium_, _Danaeites_, _Marattia_, and other genera. In such species of Taeniopteroid leaves as have been dealt with in a former Chapter, the occurrence of sori justifies the substitution of a name denoting a close relationship to existing members of the Marattiaceae, but in the absence of fertile specimens the provisional designation _Taeniopteris_ should be retained. It is often difficult to decide between _Taeniopteris_ and _Nilssonia_ as the more suitable name to apply to fragments of fossil leaves of Mesozoic age. _Taeniopteris_ is, however, distinguished from the Cycadean genus by the greater prominence of the rachis, also by the dichotomous branching of the secondary veins, usually close to their origin and at varying distances between the axis of the frond and the edge of the lamina. The genus _Taeniopteris_, though most abundant in Rhaetic and Jurassic strata, occurs also in Upper Carboniferous and Lower Permian rocks. The generic name _Macrotaeniopteris_ instituted by Schimper[1257] has been used for leaves differing only in size from the usual type of _Taeniopteris_, but there is no adequate reason for its retention.

The species included in _Taeniopteris_ afford no satisfactory evidence as to their systematic position. It is obviously unwise to adopt such generic titles as _Oleandridium_, _Marattiopsis_, etc., merely because of resemblance in the venation of sterile fragments to _Oleandra_ or Marattiaceous ferns.

Some specimens of _Taeniopteris_ fronds described by Mr Sellards[1258] from Permian rocks of Kansas, which are referred to later, have furnished unconvincing evidence of reproductive organs.

_Taeniopteris multinervis_, Weiss. Fig. 329, A, B.

The late Dr Weiss[1259] instituted this species (which he designated _Taeniopteris multinervia_, though the specific name _multinervis_ is constantly used) for a fragment of a leaf from the Lower Permian of Lebach characterised by numerous forked veins given off at right angles from a prominent rachis (fig. 329, B). This type of frond is recorded from the Permian of Trienbach (Alsace) by Zeiller[1260], by Renault[1261] and Zeiller[1262] from the Upper Carboniferous of Autun, and from other localities. The lamina of the simple leaf reaches a breadth of 6 cm. and a length of 40 cm. (fig. 329, A); the numerous secondary veins (25–36 per cm. of lamina) are either at right angles to the rachis or given off at an acute angle. The mesophyll consists of polygonal cells some of which are elongated at right angles to the surface of the lamina. A very similar form is described by Fontaine and White from the Permian of Virginia as _T. Lescuriana_[1263].

A. _Taeniopteris multinervis_, Weiss. (⅚ nat. size. After Zeiller.)
B. _T. multinervis._ (Enlarged. After Zeiller.)
C. _Lesleya Delafondi._ (× 2. After Zeiller.)]

It is futile to expect to be able to separate the numerous _Taeniopteris_ leaves into well-defined species: all we can do is to group the specimens under different names, using as artificial distinctions such characters as the shape of the leaf, the number of veins per centimetre, and the prominence of the rachis. Another Virginian species of Permian age described by Fontaine and White[1264], _T. Newberriana_, is said to bear sori, but no satisfactory information is given as to the nature of these organs. Specimens referred with some hesitation to this species and to a similar species, _T. coriacea_, have been described by Sellards[1265] from material obtained from Permian beds in Kansas. The lamina of the simple linear fronds is characterised by the occurrence of small oval bodies half immersed in the substance of the leaf between the secondary veins (figs. 330, D, E). One of these bodies is represented in an apparently dehisced condition in fig. 330, D. Sellards suggests the possibility that these bodies are sporangia, but, as he points out, they afford no indication of cellular structure nor are they in direct connexion with the veins.

_Taeniopteris jejunata_, Grand’Eury[1266].

This species differs from _T. multinervis_ in its bipinnate fronds; the linear or oval-linear pinnae are attached by a short stalk to the primary rachis and reach a length of 25 cm.; the veins are less crowded, 12–15 per centimetre.

_T. jejunata_ is recorded from the Coal-fields of the Loire and Commentry[1267] in France, from the Lower Permian of Thuringia[1268], and elsewhere.

_Taeniopteris Carnoti_, Ren. and Zeiller[1269]. Fig. 330, A.

This species, founded on portions of pinnate fronds from the Coal-field of Commentry, is characterised by rather broader (25–30 mm.) pinnules, with short pedicels and a cordate base, reaching a length of 25–30 cm. The secondary forked veins are more numerous than in _T. jejunata_. In _T. multinervis_ the pinnules are still broader and have a stronger midrib.

• • • • •

Several species of _Taeniopteris_ have been described from Triasso-Rhaetic rocks in Europe, India, Tonkin and elsewhere. In some cases it is practically impossible to recognise clear specific distinctions between Rhaetic and Jurassic types.

From the Damuda and Panchet series of India (Triasso-Rhaetic) Feistmantel has described large sterile fronds as _Macrotaeniopteris Feddeni_[1270] which reach a breadth of 20 cm.: these may be compared with the Indian species _Taeniopteris lata_ Oldham[1271], and to _T. gigantea_ from the Rhaetic of Franconia[1272] and Scania. A specimen of this species figured by Nathorst[1273] from Scania has a lamina 33 cm. broad. Other examples are afforded by _M. Wianamattae_ Feist.[1274] from rocks of the same age in Australia and by _Taeniopteris superba_ Sap.[1275] from Lower Rhaetic rocks near Autun.

From the Rhaetic of Tonkin, Zeiller records several species, among which may be mentioned _T. Jourdyi_ Zeill.[1276] and _T. spatulata_ MacClelland (fig. 330, B, C). Both have simple fronds. Those of _T. Jourdyi_ reach a length of 10–40 cm. and a breadth of 10–70 mm.; the rachis is characterised by crowded and discontinuous transverse folds, and the secondary veins (35–50 per cm.) are usually at right angles to the rachis. This Tonkin species is compared by Zeiller with the European Rhaetic species _T. tenuinervis_ Brauns.

The polymorphism of the fronds is a striking feature: in one case described by Zeiller the lamina appears to be divided into segments like those characteristic of the leaf of the Cycadean genus _Anomozamites_. It is obviously difficult in many instances to distinguish between detached Taeniopteroid pinnae of a compound frond and complete simple leaves. In some compound fern fronds, as in the recent Polypodiaceous genus _Didymochlaena_, the pinnules are deciduous, and the same feature undoubtedly characterised the fronds of many extinct species. A specimen figured by Zeiller which shows several petioles of _T. Jourdyi_ attached to a thick stem[1277] demonstrates the simple nature of the leaves. In other cases, e.g. _T. vittata_, specimens occur in which the slightly enlarged petiole-base has a clean-cut surface indicating abscission from a rhizome (fig. 332).

The fronds described by Zeiller as _T. spatulata_[1278] (fig. 330, B, C) closely resemble Jurassic leaves from Victoria referred to _Taeniopteris Daintreei_ McCoy[1279].

A. _Taeniopteris Carnoti_, Ren. and Zeill. (Nat. size. After
Renault and Zeiller.)
B. _T. spatulata_, McClell. (Nat. size. After Zeiller.)
C. _T. spatulata._ (× 3. After Zeiller.)
D. Supposed sporangium of _T. coriacea._ (× 15. After Sellards.)
E. _T. coriacea._ (× 2. After Sellards.)]

Whether specifically identical or not, these leaves represent a type distinguished from the other species of the genus by the small breadth of the linear-lanceolate or linear-spathulate lamina, which may be 6–15 cm. in length and 3–12 mm. broad. The lamina is often characterised by transverse folds (fig. 330, C).

_Taeniopteris Carruthersi._ Fig. 331.

1872. _Taeniopteris Daintreei_, Carruthers, Quart. Journ. Geol. Soc.
Vol. XXVIII. Pl. XXVII. fig. 6.

1883. _T. Carruthersi_, Tenison-Woods, Proc. Linn. Soc. N. S. Wales,
Vol. VIII. p. 117.

The simple fronds included under this specific name are characterised by a strong midrib from which numerous simple or forked secondary veins are given off at a right angle or slightly inclined. The breadth of the lamina decreases gradually towards the petiole. The Australian species named by McCoy _Taeniopteris Daintreei_, to which Carruthers referred the Queensland fossils, has a much narrower and more linear form of frond, and for this reason Tenison-Woods instituted a new specific name. _T. Carruthersi_ represents a form of leaf met with in Rhaetic, or possibly Upper Triassic, rocks in S. Africa[1280] and Australia. A very similar, perhaps an identical type, was described from Argentina by Geinitz[1281] as _T. mareyiaca_: among many other examples of this form of frond may be mentioned _T. immersa_[1282] Nath. from the Rhaetic rocks of Scania and _T. virgulata_ from the Rhaetic of Tonkin[1283].

A comparison of _Taeniopteris Carruthersi_ or various other “species” of Rhaetic fronds with the Jurassic species _T. vittata_ illustrates the slight and unimportant differences on which specific separation is based. It is hopeless to attempt to draw a satisfactory distinction between the numerous Taeniopteris fronds from Upper Triassic and Jurassic rocks.

_Taeniopteris vittata_, Brongniart. Fig. 332.

The simple leaves to which Brongniart applied this name are characteristic of the Inferior Oolite flora of England, and examples of the same type are recorded from Jurassic rocks of India, Poland, the Arctic regions, Japan, China, Australia and other countries[1284].

Leaf linear-lanceolate, reaching a length of more than 20 cm. and
a breadth of 3 cm. The lamina increases gradually in breadth from
the base and tapers towards the apex. Numerous secondary veins are
given off at right angles from a broad midrib: the lateral veins
may be simple or forked close to their origin, near the margin, or
in the intermediate portion, of the lamina.

It is exceedingly difficult to use _Taeniopteris_ leaves of this form as evidence in regard to the Jurassic or Rhaetic age of plant-bearing strata. The species _T. tenuinervis_ Brauns, as figured by Schenk[1285] from the Rhaetic rocks of Germany and Persia, and recorded from several other regions, presents a close agreement with _T. vittata_. _Oleandridium lentriculiforme_ Etheridge[1286] from the Hawkesbury series of Australia is another similar leaf. The species _T. vittata_ from the Yorkshire coast, represented in fig. 332, shows a well-preserved petiole with a clean-cut base like that of the petioles of _Oleandra neriiformis_ and other recent ferns which are detached from the rhizome by the action of an absciss-layer.

A broader form of frond with similar venation was described by Lindley and Hutton[1287] as _Taeniopteris major_. An examination of the type-specimen from the Inferior Oolite of Yorkshire, now in the Manchester Museum, led me to doubt the necessity of specific separation from _T. vittata_[1288].

A smaller frond of the same general type as _T. vittata_ is recorded from Wealden strata of North Germany and England under the name _T. Beyrichii_[1289].

Weichselia.

This generic name was instituted by Stiehler[1290] for impressions of bipinnate sterile fronds, presumably ferns, from Lower Cretaceous rocks near Quedlinburg. The same type of leaf from English Wealden beds had previously been referred by Mantell and other authors to _Pecopteris_, and by Brongniart to his genus _Lonchopteris_[1291]. It is, however, advisable to follow Nathorst’s example[1292] and restrict the latter name to Palaeozoic species. As already suggested, it would obviate confusion to substitute a new generic designation for _Lonchopteris_ in the case of Triassic species which are probably members of the Osmundaceae. The type-species of Stiehler, _Weichselia Ludowicae_[1293], does not differ in any important character from _Weichselia Mantelli_, the species originally described by Stokes and Webb from the Wealden of England as _Pecopteris reticulata_.

_Weichselia Mantelli_ (Brongn.)[1294]. Fig. 333.

1824. _Pecopteris reticulata_, Stokes and Webb, Trans. Geol. Soc.
[2]. Vol. I. p. 423, Pls. XLVI. XLVII.

1828. _Lonchopteris Mantelli_, Brongniart, Prod. p. 6; Hist. vég.
foss. p. 369, Pl. CXXXI.

1894. _Weichselia Mantelli_, Seward, Wealden Flora, Vol. I. p. 114.
Pl. X. fig. 3.

1899. _Weichselia reticulata_, Fontaine, in Ward, Ann. Rep. U. S.
Geol. Surv. p. 651.

Frond bipinnate, rachis broad; pinnae very long, of uniform breadth
and with prominent axes; pinnules crowded, entire, with obtuse
apex, usually oblong but more or less triangular or rounded towards
the distal ends of the pinnae. The pinnules, which may reach a
length of 9 cm., are characterised by a fleshy lamina attached by
the whole breadth of the base; the two rows of segments on each
secondary rachis are usually inclined towards one another so that
they form with the axis of the pinna a wide-open =V= instead of
lying in one plane (fig. 333, C). From a median rib are given off
numerous anastomosing branches (fig. 333, B).

A. Part of a frond from the Wealden of Sussex, England. (British
Museum; v. 2630. ¾ nat. size.)
B. Pinnule from Bernissart, Belgium (× 3).
C. _Weichselia erratica_, Nath. Section of pinna. (After Nathorst.)]

This characteristic Wealden species is recorded from England, Germany, France, Belgium, Austria, Russia, Bornholm, North America, and Japan. It is by no means certain that _Weichselia Mantelli_ is a true fern: no satisfactory evidence of fructification has been adduced.

The broad and strong rachis is comparable with that of a Cycadean leaf and the thick lamina suggests a plant of xerophilous habit. I have retained the specific name _Mantelli_ on the ground of long established usage instead of following Fontaine in his adherence to strict priority.

Glossopteris.

The name _Glossopteris_ was proposed by Brongniart in 1822[1295] for an imperfect leaf-impression which he called _Filicites_ (_Glossopteris_) _dubius_, but the specimen so named has since been identified as part of a sporophyll of a _Lepidostrobus_. The author of the genus afterwards published[1296] a diagnosis, based on well-preserved leaves from Permo-Carboniferous rocks in Australia and India, of the type-species _Glossopteris Browniana_, the Indian examples being distinguished as _G. Browniana_ var. _indica_ while the Australian form was named _G. Browniana_ var. _australasica_. Schimper[1297] afterwards raised the Indian fossils to specific rank as _G. indica_ though some authors[1298] have continued to consider the two forms as insufficiently distinct to be regarded as different species.

The genus _Glossopteris_ may be defined as follows:

Leaves simple, varying considerably in size, shape, and venation
characters, but almost without exception characterised by
repeatedly anastomosing lateral veins. The leaves are of two
kinds: (i) _foliage leaves_; apparently always sterile, usually
spathulate, with an obtuse apex, a well-marked midrib which may
persist to the apex or die out in the upper half of the lamina,
characterised by its slight prominence and comparatively great
breadth especially in the basal part of the frond. In most cases
the lamina extends as a narrow margin to the leaf-base, but in
a few forms there is a short petiole (fig. 334). Though usually
spathulate, the frond may be linear-lanceolate, or ovate; the
apex is sometimes acute. Leaves vary in length from 3 to 40 cm.
and may in larger forms have a breadth of 10 cm. Numerous lateral
veins curve upwards and outwards to the margin of the lamina or
pursue a straight course almost at right-angles to the midrib. (ii)
_Scale-leaves_[1299] which differ from the foliage-leaves in their
much smaller size and in the absence of a midrib; they are deltoid,
oval or cordate in shape and generally terminate in an acute apex;
the edge of the lamina may be slightly incurved so that the leaf
presents a convex upper surface supplied with anastomosing veins.
The scale-leaves, which vary in length from about 1 to 6 cm.,
probably acted as sporophylls. The only evidence as to the nature
of the fructification so far obtained is represented by empty
sporangium-like organs (1·2–1·5 mm. long by 0·6–0·8 mm. broad)
frequently associated with the scale-leaves[1300].

The leaves, in some cases at least, were borne near together on a
cylindrical stem or rhizome which produced branched adventitious
roots[1301]. The fossils long known as _Vertebraria_ were
recognised by Zeiller[1302] and by Oldham[1303] as the stems of
_Glossopteris_.

The systematic position of _Glossopteris_ must for the present be left an open question. Though usually spoken of as a fern, it is noteworthy that despite the enormous abundance of its foliage leaves in the Permo-Carboniferous strata of India, Australia, South Africa, and South America, no single example has been discovered which shows undoubted remains of sori or sporangia. Many authors have described fertile leaves of _Glossopteris_; but it was not until Arber’s discovery of sporangia in close association with the scale-leaves that any light was thrown on the nature of the reproductive organs.

The probability is that _Glossopteris_ was not a true fern but a member of that large and ever-increasing class, the Pteridosperms. This opinion is based largely on negative evidence. Such sporangia as have been described may have contained microspores and the plant may have been heterosporous. The occurrence of seeds in association with Glossopteris fronds recorded by more than one writer[1304], though by no means decisive and possibly the result of chance association, is favourable to this view. Dr White[1305] has suggested that the small leaves described by Zeiller[1306] as _Ottokaria bengalensis_ from Lower Gondwana (Permo-Carboniferous) rocks of India, and similar fossils recorded by himself from Brazil as _O. ovalis_, may represent “sporangiferous” organs of _Glossopteris_ or _Gangamopteris_, “both of which are probably pteridospermic.” There is, however, no conclusive evidence in support of this suggestion.

The genus, whatever its position may be, has a special interest for the geologist and for the student of plant distribution; it is a characteristic member of a Permo-Carboniferous flora which flourished over an enormous area, including India, South Africa,—extending from Cape Colony to Rhodesia and German East Africa[1307],—Australia, and South America[1308]. This flora, known as the Glossopteris flora, differed considerably in its component genera from that which overspread Europe and North America and some more southern regions in the Upper Carboniferous and Permian periods.

The discovery by Amalitzky[1309] of _Glossopteris_, and other genera characteristic of the Glossopteris flora, in the Upper Permian rocks in Vologda (Russia) demonstrates the existence of a northern outpost of the southern botanical province, and Zeiller’s discovery of the genus in the Rhaetic flora of Tonkin[1310] shows that _Glossopteris_ persisted beyond the limits of the Palaeozoic epoch. Dr David White[1311] has recently proposed to re-christen the Glossopteris flora the Gangamopteris flora on the ground that _Gangamopteris_ is strictly Palaeozoic in its range, whereas _Glossopteris_ persisted into the Mesozoic era; this is perhaps hardly a sufficient reason for giving up so well established a title as the Glossopteris flora. A fuller account of this southern flora must be reserved for another volume.

_Glossopteris Browniana_, Brongniart[1312]. Figs. 334–36.

The specific name _Browniana_ is now applied to obtusely pointed leaves which sometimes reach a length of 15 cm., but are usually rather shorter. In form and venation they closely resemble the leaves of the recent genus _Antrophyum_ and species of _Acrostichum_. The comparatively broad midrib may be replaced in its proximal portion by several parallel veins: from it are given off numerous lateral veins which form a reticulum characterised by meshes approximately equal in size and elongated in a direction parallel to the general course of the secondary veins (fig. 334).

The drawings, originally published by Zeiller[1313], reproduced in fig. 335 illustrate the venation and its range of variation; the meshes are usually hexagonal and arranged as shown in figs. A and B, but occasionally (fig. 335, C) they follow a more steeply inclined course.

Small leaves with a more or less distinct midrib, 2–3 cm. in length, supply transitional stages between foliage- and scale-leaves. In the true scale-leaves spreading and occasionally anastomosing veins take the place of the midrib and lateral veins of the ordinary frond. McCoy[1314] in describing some Australian specimens of _Glossopteris_ in 1847 spoke of scale-like appendages of the rhizome which he compared with the large ramenta of _Acrostichum_ and other ferns. It was, however, Zeiller[1315] who first recognised the leaf-nature of these scales and adequately described them; additional figures of scale-leaves have been published by Mr Arber[1316] and by myself[1317]. The importance of these small leaves has been considerably increased by Mr Arber’s discovery of associated sporangia which, as he suggests, were probably borne on their lower concave surface.

The sporangia (fig. 336) are compared by Arber with the microsporangia of recent Cycads and with the Palaeozoic sporangia described by Zeiller as _Discopteris Rallii_ (fig. 256, D); the latter are distinguished by the well-defined group of thicker walled cells representing the annulus of true fern sporangia. We know nothing as to the contents of the Glossopteris sporangia, whether they contained microspores or whether they are the spore-capsules of a homosporous plant.

The rhizome of _Glossopteris Browniana_ has been described in detail by Zeiller, who first demonstrated that the fossils originally assigned by Royle[1318] to the genus _Vertebraria_ represent the stem of this and, as we now know, of some other species of _Glossopteris_. _Vertebraria_ occurs in abundance in Permo-Carboniferous strata in association with _Glossopteris_; the differences between Australian, Indian, and South forms, though expressed by specific names, are insignificant. The stems are usually preserved in the form of flattened, single or branched, axes sometimes bearing slender branched roots and characterised by one or two, or less frequently three, longitudinal grooves or ridges (fig. 337) from which lateral grooves or ridges are given off at right angles, dividing the surface into more or less rectangular areas 1 cm. or more in length. The surface of these areas is often slightly convex and in some specimens the outlines of cells may be detected. Mr Oldham has described some interesting examples of _Vertebraria_ from India in which the longitudinal and transverse grooves are occupied by a dark brown ferruginous substance or by the carbonised remains of plant-tissues (fig. 338, C, D). In transverse section, a _Vertebraria_ cast appears to be divided into a number of wedge-shaped segments radiating from a common centre. Prof. Zeiller[1319] has figured specimens of _Vertebraria_ with portions of Glossopteris fronds still attached.

The rhizome of _Glossopteris_, as represented by the Vertebraria casts, is aptly compared by Zeiller[1320] with that of the recent Polypodiaceous fern _Onoclea struthiopteris_. Sections of the recent stem (fig. 338, E, F) show that the form is irregularly stellate owing to the presence of prominent wings which anastomose laterally at intervals as shown by the examination of a series of sections. The leaf-traces are derived from the steles of adjacent wings. Fig. 338 (B and A) represents somewhat diagrammatically a longitudinal and transverse view of a _Vertebraria_; the radiating arms represented in the transverse section (fig. A) are the stem ribs or wings and the segments between them are intrusions of sedimentary material. The rectangular areas characteristic of the surface of a _Vertebraria_ are the intruded segments of rock: these are separated at intervals by transverse grooves, which mark the course of vascular strands given off at each anastomosis of the longitudinal wings to supply the leaves.

A, B. _Vertebraria indica._ (After Zeiller.)
C, D. _V. indica._ (Nat. size. After Oldham.)
E, F. _Onoclea struthiopteris._ (× 2. After Zeiller.)]

Mr Oldham, who discovered the connexion between _Glossopteris_ and _Vertebraria_ independently of Dr Zeiller, does not agree with the interpretation of the structural features of the rhizome which Zeiller bases on a comparison between Vertebraria and _Onoclea struthiopteris_. Oldham[1321] describes _Vertebraria_ as consisting of a central axis “joined to an outer rind by a series of radial septa,” the spaces between the septa being divided into chambers by transverse partitions. His view is that the rhizome of _Glossopteris_ was a cylindrical organ and not an irregularly winged axis like the stem of _Onoclea_. Zeiller[1322] has replied in detail to Oldham’s interpretation and adheres to his original view, that the rhizome consisted of a solid axis with radial wings or flanges which at intervals anastomosed transversely in pairs at the nodes. It may, however, be possible that the spaces between the longitudinal and transverse grooves on a Vertebraria axis, which have been filled with the surrounding rock, were originally occupied in part at least by secondary wood, and the transverse strips of carbonaceous material[1323] lying in the grooves may represent medullary-ray tissue and accompanying leaf-traces. The longitudinal striations seen in some specimens of _Vertebraria_ on the areas between the grooves may be the impressions of woody tissue. It is impossible without the aid of more perfectly preserved material to arrive at a satisfactory conception of the structural features of a complete Glossopteris rhizome.

In the specimen of _Glossopteris Browniana_ shown in fig. 339 several leaves are attached to an axis which shows none of the surface-features of _Vertebraria_. I am indebted to the kindness of Dr Mohlengraaff of Delft for the loan of this specimen which was obtained from Permo-Carboniferous rocks in the Transvaal. An axis figured by Etheridge[1324] from an Australian locality bears a tuft of _Glossopteris_ leaves, possibly _G. Browniana_; in place of the rectangular areas characteristic of _Vertebraria_ it shows transversely elongated leaf-scars or, on the internal cast, imbricate rod-like projections which Etheridge suggests represent vascular bundles.

_Glossopteris indica_, Schimper. Figs. 340, A, 341.

It is a question of secondary importance whether or not the fronds which Brongniart spoke of as a variety of _Glossopteris Browniana_ should be recognised as specifically distinct. The careful examination by Zeiller of the venation characters has, however, afforded justification for separating _G. Browniana_ and _G. indica_. We must admit that the slight and not very constant differences in the size and form of the meshes produced by the anastomosing of the lateral veins are characters which cannot be recognised as having more than a secondary value, though, as a matter of convenience, we employ them as aids to determination. The arbitrary separation of sterile leaves, which differ by small degrees from one another in form and in the details of venation, by the application of specific names is a thankless task necessitated by custom and convenience; it is, however, idle to ignore the artificial basis of such separation. Mr Arber has recently published, in his valuable _Glossopteris Flora_, an analytical key which serves to facilitate the description and determination of different types of frond[1325].

A. _Glossopteris indica_, Schimper. (½ nat. size.)
B. _Glossopteris angustifolia_, Brongniart. (Nat. size.) From Arber,
after Feistmantel.]

The large leaves of _Glossopteris indica_, reaching a length in extreme cases of 40 cm. and a breadth of 10 cm., are characterised by a rather greater regularity in the arrangement of the meshes and by the greater parallelism of the upper and lower sides of each mesh (fig. 341) and by less difference in size between the venation meshes than in _G. Browniana_, the leaves of which are usually smaller. The relatively thick epidermis consists of rectangular cells with stomata in depressions[1326]. The scale-leaves[1327], rather larger than those of _G. Browniana_, are more or less rhomboidal with rounded angles and reach a length of 1·5–6 cm. and a breadth of 1·5–2·5 cm. The rhizome is practically identical with that of _G. Browniana_[1328].

This species occurs in great abundance in the Permo-Carboniferous rocks of India, Australia, and in various parts of South Africa, and elsewhere. It has been recognised also by Amalitzky[1329] in Upper Permian beds in Russia and by Zeiller in the Rhaetic series of Tonkin[1330].

_Glossopteris angustifolia_, Brongniart. Figs. 340, B; 342.

It is convenient to retain this designation for linear fronds with an acute or obtuse apex and a venation-reticulum composed of long and narrow meshes (fig. 340, B). It is by no means unlikely, as Arber suggests, that the same plant may have produced leaves of the _G. indica_ type and narrower fronds which conform to _G. angustifolia_. In his description of some Indian specimens of _G. indica_, Zeiller draws attention to the variation exhibited in regard to the extent of anastomosing between the secondary veins: some examples with very few cross-connexions agree more closely with _Taeniopteris_ than with _Glossopteris_ as usually defined[1331]. The venation shown in fig. 342 illustrates an extreme case of what is almost certainly a Glossopteris leaf of the _G. angustifolia_ type. This specimen, which was discovered by Mr Leslie in the Permo-Carboniferous sandstone of Vereeniging (Transvaal), has been referred to a variety of Brongniart’s species as _G. angustifolia_ var. _taeniopteroides_[1332] on account of the almost complete absence of any cross-connexions. The reference to _Glossopteris_, which my friend Dr Zeiller suggested, is amply justified by the form of the leaf as a whole, by the angle at which the lateral veins leave the midrib, a feature in contrast to the wider angle at which the lateral veins are usually given off in _Taeniopteris_ (figs. 329, 332), and by the similarity to the Indian specimens already mentioned. Several authors have described leaves or leaflets under the generic name _Megalopteris_[1333] from Carboniferous and Permian rocks which bear a close resemblance to the South African variety, but in some cases at least _Megalopteris_ is known to be a pinnate and not a simple leaf. The leaf figured by Jack and Etheridge as _Taeniopteris_ sp.[1334] from Queensland may also be an example of _Glossopteris_. Comparison may be made also with the Palaeozoic leaves described in the first instance by Lesquereux and more recently by Renault and Zeiller as species of _Lesleya_[1335] (fig. 347).

_Blechnoxylon talbragarense_, Etheridge. Fig. 343.

Under this name Etheridge[1336] described some specimens from the Permo-Carboniferous Coal-Measures of New South Wales, which he regards as a fern, comparable, in the possession of a cylinder of secondary xylem, with the recent genus _Botrychium_ and with _Lyginodendron_ and other members of the Cycadofilices. The slender axis (1–3 mm. in diameter) appears to consist of a zone of radially disposed tissue (fig. 343, C, _x_), which is probably of the nature of secondary xylem, enclosing a pith and surrounded externally by imperfectly preserved remnants of cortex. Unfortunately no anatomical details could be made out, but the general appearance, if not due to inorganic structure, certainly supports Etheridge’s determination. The stem bore at intervals clusters of linear-lanceolate leaves (reaching 12 mm. in length) in close spirals (fig. 343, A and B); the leaves are characterised by a strong midrib and forked secondary veins. Small “pyriform” bodies of the nature of scale-leaves occur in association with the fronds (fig. 343, B, _s_).

In his description of this interesting plant, Etheridge quotes an opinion which I expressed in regard to the comparison of the stem with those of _Botrychium_, _Lyginodendron_, and other genera. No satisfactory evidence has been found as to the nature of the fructification. Although the leaves of _Blechnoxylon_ are much smaller than those of _Glossopteris_, I am now disposed to regard the genus as closely allied or even generically referable to _Glossopteris_. The crowded disposition of the leaves is like that in _Glossopteris_, shown in fig. 339 and in the figures published by Etheridge and by Oldham; the association of scale-leaves and foliage-leaves is another feature in common. The absence of a reticulum of anastomosing veins can no longer be considered a fatal objection to the suggestion that the Australian type may be a species of _Glossopteris_. If the view that _Blechnoxylon_ is not a distinct genus is correct, the occurrence of secondary xylem is favourable to the opinion already expressed that _Glossopteris_ is more likely to be a Pteridosperm than a true fern. The data at present available render it advisable to retain Mr Etheridge’s name: the comparison with _Glossopteris_ lacks confirmation.

[Sidenote: BLECHNOXYLON]

_Glossopteris retifera_, Feist. Fig. 344.

In some _Glossopteris_ leaves the anastomosing secondary veins form a coarser reticulum, as in the example represented in fig. 344. The name _G. retifera_ was given by Feistmantel[1337] to Indian fronds of this type; similar forms have been described as _G. conspicua_ and _G. Tatei_. The type illustrated by _G. retifera_ is recorded also from Permo-Carboniferous rocks in Zululand[1338], Natal, the Transvaal, Cape Colony, and the Argentine.

Gangamopteris.

In 1847 McCoy[1339] described a leaf-fragment from Permo-Carboniferous rocks in New South Wales as _Cyclopteris angustifolia_. The type-specimen of this species, which is now in the Sedgwick Museum, Cambridge, has been re-described by Mr Arber[1340]. Subsequently[1341] McCoy instituted the generic name _Gangamopteris_ for leaves, like that previously referred by him to _Cyclopteris_, from the Bacchus Marsh Sandstone, of New South Wales, but he did not publish a diagnosis of the genus until several years later[1342]. Feistmantel[1343], who has described many species of _Gangamopteris_ from the Lower Gondwana strata of India, slightly modified the original diagnosis. The genus is represented by sterile fronds only. We know nothing of the stem, and such evidence as is available in regard to the form of the fertile leaves is of a circumstantial kind. It is, however, highly probable that _Gangamopteris_ is not a true fern but a Pteridosperm.

Leaves simple, sessile, varying in shape; obovate or spathulate,
broadly lanceolate or rarely linear; the apex is usually blunt
(fig. 345) but occasionally gradually tapered. In general
appearance a Gangamopteris leaf is similar to that of _Glossopteris
indica_, the chief distinction being the absence of a midrib.
Gangamopteris leaves are on the whole larger than those of
_Glossopteris_; many of them reach a length of 20 cm. and some of
the large Indian fronds are nearly 40 cm. long. The venation of
_Gangamopteris_ shows a greater uniformity in the size and shape
of the meshes than that of _Glossopteris_. The middle of the
lamina, especially in the lower part, is occupied by a few vertical
veins from which branches curve upwards and outwards towards the
edge of the lamina. The secondary veins are connected by frequent
anastomoses and agree very closely with those of _Glossopteris_.
The lamina becomes narrower towards the base, which is either
cuneate or in some cases slightly auriculate (fig. 345).

As I have elsewhere pointed out[1344], the presence or absence of a midrib is not in itself a character of real taxonomic importance. In the recent fern _Scolopendrium vulgare_ the frond has a prominent midrib, while in _S. nigripes_ there is no median rib. Mr Arber has expressed the opinion that “it is extremely doubtful whether the genus _Gangamopteris_ should not be merged in _Glossopteris_[1345].” The retention of the two names is, however, convenient, and it would tend to confusion were we to carry to its logical conclusion the view that the recognised distinction between the two genera may not be a mark of generic difference.

_Gangamopteris_ is confined to Palaeozoic strata, a fact which leads White[1346] to speak of the Gangamopteris rather than of the Glossopteris Flora. It occurs in South America, South Africa, Australia, and India, extending as far north as Kashmir; it has been discovered by Amalitzky in Permian rocks of Russia[1347]. The Russian rocks in which _Glossopteris_ and _Gangamopteris_ were found are no doubt of Permian age. In Australia, South Africa, Brazil and Argentina, and in the Indian Coal-fields, _Gangamopteris_ is a characteristic genus of Lower Gondwana rocks. These strata are usually spoken of as Permo-Carboniferous in order to avoid the danger of attempting on insufficient data a precise correlation with European formations.

Feistmantel speaks of _Gangamopteris_ as most abundant in the Talchir-Karharbári beds, though it is represented also in the overlying Damuda series. In Australia the genus occurs in rocks which correspond in position and in their plant fossils with the Talchir-Karharbári beds of India; similarly, in South Africa and South America the Gangamopteris beds are homotaxial with those of India and Australia. The leaf described by Carruthers[1348] from Brazil as _Noeggerathia obovata_ (the type-specimen is in the British Museum) is no doubt specifically identical with _Gangamopteris cyclopteroides_ Feist.[1349] In a paper by Mr Hayden on Gangamopteris beds in the Vihi Valley, Kashmir, evidence is adduced in support of the conclusion that the rocks are “not younger than Upper Carboniferous and may belong to the base of that subdivision or even to the Middle Carboniferous[1350].” It would seem that _Gangamopteris_ was a very widely spread genus during the latter part of the Carboniferous period in the vast Southern Continent to which the name Gondwana Land is often applied, and that it flourished in the Southern Flora during at least part of the Permian period: with other members of the Glossopteris Flora it migrated to the North where it has been preserved in Permian rocks of Northern Russia. The Glossopteris Flora must have had its birth in the Southern hemisphere. The conclusion seems inevitable that the leaves of _Glossopteris_ and _Gangamopteris_ in the shales and sandstones of India, South Africa, South America, and Australia are relics of the vegetation of a continent of which these regions are the _disjuncta membra_. Darwin wrote to his friend Hooker in 1881, “I have sometimes speculated whether there did not exist somewhere during long ages an extremely isolated continent, perhaps near the South Pole[1351].” It is probable that _Gangamopteris_ is one of the genera which flourished on this continent.

_Gangamopteris cyclopteroides_, Feistmantel[1352]. Fig. 345.

1876. Feistmantel, Records Geol. Surv. India, Vol. IX. Pt iii. p. 73.

The specimen represented in fig. 345 illustrates the characters of this commonest representative of the genus.

_Gangamopteris kashmirensis_, Seward.

1905. Seward, Mem. Geol. Surv. India, Vol. II. Mem. ii.

This type agrees closely with _G. cyclopteroides_ in size and in the form of the leaf, but it is distinguished by the flatter form of the arch formed by the lateral veins, by their greater inclination to the margin of the lamina, and by the more acutely pointed apex of the lamina. This species, though not very sharply distinguished from _G. cyclopteroides_, is important as coming from beds which have been assigned on other than palaeobotanical evidence to an Upper or possibly a Middle Carboniferous horizon[1353].

We have no definite information in regard to the nature of the reproductive organs of _Gangamopteris_, but such evidence as there is supports the view expressed by Dr White[1354] and shared by some other authors that _Gangamopteris_ and _Glossopteris_ should be assigned to the Pteridosperms. Despite the abundance of _Gangamopteris_ leaves, no fertile specimen has been discovered. This negative evidence may prove to be as correct as that which led Stur[1355] to exclude _Neuropteris_, _Alethopteris_ and _Odontopteris_ from the ferns. The only evidence of a positive kind is that furnished by Dr David White in his recent Report on the Palaeozoic Flora of South Brazil. This author describes some small Aphlebia-like leaves under two new generic names _Arberia_[1356] and _Derbyella_[1357]. The differences between the two sets of specimens, so far as can be determined from the reproductions of imperfect impressions, are slight, and it is by no means clear that a distinction of generic rank exists. These scale-leaves are on the average about 2 cm. in length; the lamina is oval or rounded and has more or less prominent lobes. In _Derbyella_ there are indications of anastomosing veins. The specimens referred to _Arberia minasica_ are, as White points out, very similar to the fossil described by Feistmantel from Lower Gondwana rocks of India as probably a portion of an inflorescence of _Noeggerathiopsis_[1358]. Feistmantel’s specimen is represented in fig. 346: the curled lobes may have originally borne seeds. In the Brazilian examples the abruptly truncated lobes “bear evidence of separation from reproductive bodies.” An important point is the association of these scale-leaves with _Gangamopteris_ fronds and with gymnospermous seeds of the _Samaropsis_ type. On the leaves assigned to _Derbyella aurita_ circular depressions occur at the base of the lobes which are described as probably due to sporangia.

Dr White’s discovery gives us increased confidence in expressing the view that _Gangamopteris_ bore its reproductive organs on specialised leaves very different from the sterile fronds; it also strengthens the suspicion that the genus is a member of the class of seed-bearing fern-like plants.

Lesleya.

This generic designation was instituted by Lesquereux[1359] for simple oval-linear leaves from the Coal-Measures of Pennsylvania. The leaves so named are probably generically identical with the specimen doubtfully assigned by Brongniart[1360] to the Coal-Measures, and made by him the type of the genus _Cannophyllites_ on the ground of a resemblance to the leaves of the recent flowering plant _Canna_. Fig. 347 illustrates the form of a _Lesleya_ leaf from the Coal-basin of Gard, named by Grand’Eury _L. simplicinervis_[1361], a type in which the veins are frequently unbranched and not repeatedly forked as in most examples of the genus (fig. 329, C). The features of the genus are, the oval-linear or lanceolate shape of the presumably simple frond, its entire or, in one species at least (_L. Delafondi_, Zeill.), finely dentate margin, the stout rachis giving off at a very acute angle numerous dichotomously branched secondary veins. In _L. Delafondi_ (fig. 329, C), described by Zeiller[1362] from the Lower Permian of Autun, the frond may reach a length of more than 20 cm. and a breadth of 8 cm. Similar species are represented by _L. ensis_[1363] from the coal-field of Commentry, and _L. grandis_[1364] from Upper Carboniferous rocks of North America. The genus is characteristic of Upper Carboniferous and Lower Permian strata: the form of the leaf and the direction of the secondary veins suggest comparison with _Glossopteris_, but in _Lesleya_ there are no cross-connexions between the veins. Nothing is known as to the fructification, a fact which naturally evokes the opinion that the genus is a Pteridosperm[1365] and not a true fern. Some years before the discovery of Pteridosperms, Grand’Eury[1366] suggested that _Lesleya_ might be a Gymnosperm; his opinion being based on the woody nature of the rachis and on the simple venation of _Lesleya simplicinervis_.

Neuropteridium.

In their monograph of fossil plants from the Bunter Series of the Vosges, Schimper and Mougeot[1367] described some pinnate leaves of ferns as species of the genus _Neuropteris_. In 1869 Schimper[1368] placed these in a new sub-genus _Neuropteridium_, in order to draw attention to the fact that their fronds appear to be simply pinnate and not bipinnate or tripinnate as in _Neuropteris_. The type-species of _Neuropteridium_ is _N. grandifolia_ Sch. and Moug. from the Bunter Sandstones of the Vosges. The genus includes Triassic European species and the widely distributed Permo-Carboniferous species from Brazil[1369] originally described by Carruthers as _Odontopteris Plantiana_. It is probable that some Carboniferous plants, particularly species from the lower members of the formation, referred to the genus _Cardiopteris_, are not genetically distinct from the Indian and southern hemisphere type _Neuropteridium validum_ (= _Odontopteris Plantiana_).

Fronds pinnate, linear; a broad rachis bears pinnules which may
be either semicircular or broadly linear with an entire or lobed
margin. The longer pinnules may exceed 6 cm. in length. The
pinnules agree with those of _Neuropteris_ in being attached by
the median portion of the lamina and not by the whole base, which
is more or less auriculate. In some cases the repeatedly forked
veins diverge from the centre of the pinnule base; in others there
is a midrib which persists for a short distance only, and in some
species the more persistent median vein gives the segments a closer
resemblance to those of _Neuropteris_. Fructification unknown,
with the exception of obscure indications of sporangia (?) on the
fertile leaves of a Triassic species.

_Neuropteridium validum._ (Feistmantel[1370]). Fig. 348.

1869. _Odontopteris Plantiana_, Carruthers, Geol. Mag. Vol. VI. p. 9,
Pl. VI. figs. 2, 3.

1878. _Neuropteris valida_, Feistmantel, Mem. Geol. Surv. India,
Foss. Flor. Gondwana Syst., Vol. III. p. 10, pl. II.–VI.

1880. _Neuropteridium validum_, Feistmantel, _Ibid._ 2, p. 84.

The specimen represented in fig. 348 illustrates the main features of _Neuropteridium validum_. This species is referred to by Dr White[1371] as _N. Plantianum_ on the ground of priority, and with a view to perpetuate the name of the English engineer Nathaniel Plant who discovered the species in a Brazilian Coal-field in the province of Rio Grande do Sul. Feistmantel’s specific name is however retained as being much better known. An examination of Mr Plant’s specimen in the British Museum led me[1372] to speak of the Brazilian species as identical with _N. validum_ described by Feistmantel from Lower Gondwana rocks of India. Zeiller[1373] had previously drawn attention to the resemblance between the two sets of specimens. The frond of _N. validum_ may exceed 50 cm. in length. The lower pinnules may be entire and semicircular in form while the upper and larger segments, which may reach a length of 5 or 6 cm., are characterised by broad lobes (fig. 348).

This type is represented in the flora of the Talchir-Karharbári series (Lower Gondwana) of India[1374], in Permo-Carboniferous rocks of Brazil and Argentine[1375], and in the sandstones of Vereeniging on the borders of the Transvaal and Cape Colony. It is a characteristic member of the Glossopteris Flora and occurs in association with _Glossopteris_ and _Gangamopteris_.

_Neuropteridium intermedium_ (Schimper). Fig. 349.

This species has been figured by Schimper and Mougeot[1376] from the Bunter of the Vosges and more fully described by Blanckenhorn[1377] from the Bunter beds of Commern. The pinnate leaves reach a length of 65 cm.; the lower semicircular pinnules pass gradually into broadly linear segments characterised by an auriculate base and a Neuropteris type of venation (fig. 354, D′, E). In the example reproduced in fig. 349 from one of Blanckenhorn’s figures, the fronds are attached to a short and thick rhizome bearing roots and portions of old petioles.

An example of another Triassic species is afforded by _Neuropteridium grandifolium_ Schimp. and Moug., which agrees very closely with _N. validum_ in the size and shape of the pinnules. The occurrence in Lower Mesozoic European rocks of fronds hardly distinguishable from the older southern species may be regarded as favourable to the view already expressed, that some at least of the Permo-Carboniferous plants migrated north of the Equator. The resemblance between the Vosges Triassic species of _Schizoneura_[1378] and the examples of this genus recorded from the Lower Gondwana rocks of India affords additional evidence of a northern migration.

Our knowledge of the reproductive organs of _Neuropteridium_ is practically _nil_. There is no doubt that Zeiller[1379] and Blanckenhorn[1380] are correct in regarding the Bunter fronds assigned by Schimper and Mougeot to the genus _Crematopteris_ as the fertile leaves of _Neuropteridium intermedium_ or some other species from the same horizon. These fronds bear crowded pinnules similar to those of _Neuropteridium intermedium_, _N. Voltzii_[1381], and other species, exhibiting on the exposed surface numerous carbonaceous spots which may be the remains of sporangia.

Cardiopteris.

Schimper[1382] applied this generic name to Lower Carboniferous fronds of a simple-pinnate habit which had previously been described as species of _Cyclopteris_. _Cardiopteris frondosa_ may serve as a typical example. This species, originally described by Goeppert as _Cyclopteris frondosa_ (fig. 350), is recorded from Lower Carboniferous rocks in the Vosges district[1383] in Silesia, Moravia[1384], and Thuringia[1385]. The pinnules, which are attached in opposite pairs to a broad rachis, vary in length from 2 to 10 cm. and have a breadth of 2 to 8 cm.; in manner of attachment and venation they agree with those of _Neuropteridium validum_. The venation is very clearly shown in a drawing of some large pinnules figured by Stur[1386].

The specimen of _Cardiopteris frondosa_, a portion of which is shown in fig. 350 on a slightly reduced scale, was originally figured by Schimper from an unusually good example in the Strassburg Museum. Schimper’s drawing hardly does justice to the original specimen.

A frond bearing rather narrower pinnules, alternately placed on the rachis, which Fritsch has described as _Cardiopteris Hochstetterii_ var. _franconica_ from the Culm of Thuringia, bears a close resemblance to _Neuropteridium validum_ but differs in the entire margin of the pinnules. An Upper Carboniferous species from Russia described by Grigoriew[1387] as _Neuropteris_, cf. _cordata_ var. _densineura_, represents another form of similar habit.

Schuster[1388] has recently proposed a new generic name _Ulvopteris_ for a fragment of a pinna from the Coal-Measures of Dudweiler in Germany bearing large pinnules, which he compares with those of _Cardiopteris_ and species of _Rhacopteris_. The specimen appears to be indistinguishable from some of those already referred to as conforming to _Neuropteridium_, and it is difficult to recognise any reason for the creation of a new generic name.

We cannot hope to arrive at any satisfactory decision in regard to the precise affinity between _Neuropteridium validum_ and species referred to _Cardiopteris_ and other genera so long as portions of sterile fronds are the only tests at our disposal. It is difficult to determine whether a specimen consisting of an axis bearing pinnules represents a large pinna of a bipinnate frond or if it is a complete pinnate leaf. There is, however, no adequate reason for supposing that the presumably pinnate fronds from the Gondwana Land rocks are generically distinct from the Lower Carboniferous European species _Cardiopteris frondosa_. Granting the probability that both genera are Pteridosperms and closely allied to one another, the two generic names may be retained on the ground of long usage and in default of satisfactory evidence confirmatory of generic identity. _Cardiopteris_ would thus stand for a type of frond characteristic of the Lower Carboniferous strata of Europe, while _Neuropteridium_ is retained for the Southern species _N. validum_, and for others from the Trias of the Vosges.

Aphlebia.

This name was proposed by Presl[1389] for large leaf-like impressions having a pinnate or pinnatifid form and characterised by a confused irregular type of venation, or by a fine superficial striation or wrinkling which simulates veins. Gutbier had previously described similar fossils as _Fucoides_, and other authors have described Aphlebiae as species of _Rhacophyllum_, _Schizopteris_, and other genera[1390]. The term _Aphlebia_ is retained, not as denoting a distinct genus but (i) as a descriptive name for detached leafy structures similar to those figured by Presl, which are now recognised as laminar appendages of the petioles of ferns or fern-like fronds, and (ii) as an epithet for highly modified pinnules which frequently occur at the base of the primary pinnae of Pecopteroid and Sphenopteroid fronds (e.g. _Dactylotheca plumosa_, fig. 293)[1391].

Modified pinnules, similar in their reduced and deeply dissected lamina to those represented in fig. 293, are frequently found at the base of the primary pinnae of Palaeozoic species of _Sphenopteris_ and other genera of Pteridosperms or ferns, including members of the Coenopterideae. Potonié[1392] gives a list of various types of Aphlebiae in his paper on these organs. A striking case has recently been described by Zeiller in a French Upper Carboniferous species, _Sphenopteris Matheti_[1393]. It would seem that the larger examples of Aphlebiae are more frequently associated with the compound leaves of Pteridosperms than with those of Ferns[1394].

As examples of the larger types of Aphlebiae reference may be made to _Aphlebia crispa_ (Gutb.)[1395], which reaches a length of nearly 60 cm. and has the form of a more or less triangular pinnate leaf divided into decurrent deeply lobed segments, to a similar species represented by _A. Germari_ (= _Schizopteris lactuca_ Germ.)[1396] which simulates the leaves of endive (_Cichorium endivia_ L.), and to some large forms figured by Grand’Eury[1397] as species of _Schizopteris_.

Aphlebiae such as that figured by Kidston[1398] as _Rhacophyllum crispum_, with narrow ultimate segments, might easily be mistaken for the impressions of an alga.