Chapter IX: PTERIDOPHYTA (Vascular Cryptogams) (2)

This species is described at some length as affording a useful illustration of the misleading character of certain features which are entirely due to methods of preservation. The specific name was proposed by Phillips in his first edition of the _Geology of the Yorkshire Coast_ for some very imperfect stems from the Lower Oolite rocks near Whitby[524]. The choice of the term _lateralis_ illustrates a misconception; it was given to the plant in the belief that certain characteristic wheel-like marks on the stems were the scars of branches. Lindley and Hutton[525] figured a specimen of this species in their _Fossil Flora_, and quoted a remark by “Mr Williamson junior” (afterwards Prof. Williamson) that the so-called scars often occur as isolated discs in the neighbourhood of the stems. Bunbury[526] described an example of the same species with narrow spreading leaves like those of a Palaeozoic _Asterophyllites_, and proposed this generic name as more appropriate than _Equisetites_. In all probability the example shown in fig. 63 is that which Bunbury described. It is certainly the same as one figured by Zigno[527] as _Calamites lateralis_ in his _Flora fossilis formationis Oolithicae_.

This specimen illustrates a further misconception in the diagnosis of the species. The long linear appendages spreading from the nodes are, I believe, slender branches and not leaves; they have not the form of delicate filmy markings on the rock face, but are comparatively thick and almost woody in appearance. The true leaves are distinctly indicated at the nodes, and exhibit the ordinary features of toothed sheaths.

Heer[528] proposed to transfer Phillips’ species to the genus _Phyllotheca_, and Schimper[529] preferred the generic term _Schizoneura_. The suggestion for the use of these two names would probably not have been made had the presence of the _Equisetum_ sheaths been recognised.

The circular depressions a short distance above each node are the ‘branch scars’ of various writers. Schimper suggested that these radially marked circles might be displaced nodal diaphragms. Andrae[530] figured the same objects in 1853 but regarded them as branch scars, although in the specimen he describes, there are several of them lying apart from the stems, and to one of them is attached a portion of a leaf-sheath. Solms-Laubach[531] points out that the internodal position of these supposed scars is an obvious difficulty; we should not expect to find branches arising from an internode. After referring to some specimens in the Oxford museum, he adds—“In presence of these facts the usual explanation of these structures appears to me, as to Heer, very doubtful.... We are driven to the very arbitrary assumption that they represent the lowest nodes of the lateral branches which were inserted above the line of the nodes of the stem.” Circular discs similar to those of _E. lateralis_ have been found in the Jurassic rocks of Siberia[532] and elsewhere. There are one or two examples of such discs from Siberia in the British Museum. If the nodal diaphragms were fairly hard and stout, it is easy to conceive that they might have been pressed out of their original position when the stems were flattened in the process of fossilisation. It is not quite clear what the radial spoke-like lines of the discs are due to; possibly they mark the position of bands of more resistant tissue or of outgoing strands of vascular bundles. A detached diaphragm is seen in fig. 64 C; in the centre it consists of a flat plate of tissue, and the peripheral region is traversed by the radiating lines. In the stem of fig. 64, A the deeply divided leaf-sheaths are clearly seen, and an imperfect impression of a diaphragm is preserved on the face of the middle internode. In fig. 64 B a flattened leaf-sheath is shown with the free acuminate teeth fused basally into a continuous collar[533]. The short piece of stem of _Equisetites lateralis_ shown in fig. 58, _F_, shows how the free teeth may be outspread in a manner which bears some resemblance to the leaves of _Phyllotheca_, but a comparison with the specimens already described, and a careful examination of this specimen itself, demonstrate the generic identity of the species with _Equisetites_. The carbonaceous film on the surface of such stems as those of fig. 58, F, and 64, A, shows a characteristic shagreen texture which may possibly be due to the presence of silica in the epidermis as in recent Horse-tails.

There is another species of _Equisetites_, _E. Münsteri_, Schk., from a lower geological horizon which has been compared with _E. lateralis_, and lends support to the view that the so-called branch-scars are nodal diaphragms[534]. This species also affords additional evidence in favour of retaining the generic name _Equisetites_ for Phillips’ species. _Equisetites Münsteri_ is a typical Rhaetic plant; it has been found at Beyreuth and Kuhnbach, as well as in Switzerland, Hungary and elsewhere. A specimen of _Equisetites_ originally described by Buckman as _E. Brodii_[535], from the Lower Lias of Worcestershire, may possibly be identical with _E. Münsteri_. The leaf-sheaths of this Rhaetic species consist of broad segments prolonged into acuminate teeth; some of the examples figured by Schenk[536] show clearly marked impressions of displaced nodal diaphragms exactly as in _E. lateralis_. Another form, _Equisetum rotiferum_ described by Tenison-Woods[537] from Australia, is closely allied to, or possibly identical with _E. lateralis_.

8. _Equisetites Burchardti_ Dunker[538]. Fig. 65.

This species of _Equisetites_ is fairly common in the Wealden beds of the Sussex coast near Hastings, and also in Westphalia.

It is characterised by having long and slender internodes, bearing at the nodes leaf-sheaths with five or six pointed segments, and by the frequent formation of branch-tubers. These tuberous branches closely resemble those which are formed on the underground shoots of _Equisetum arvense_ L., _E. sylvaticum_ L. and others; they occur either singly or in chains[539]. In the specimen shown in the figure the left-hand tuber is remarkably well preserved, its surface is somewhat sunk and shrivelled, and the apex is surrounded by a nodal leaf-sheath. A thin branched root is given off just below the point of insertion of the oval tuber.

No other species of _Equisetites_ affords such numerous examples of tubers as this Wealden plant. By some of the earlier writers the detached tubers of _E. Burchardti_ were described as fossil seeds under the name _Carpolithus_.

The specimens shown in fig. 66 have been referred to another species, _E. Yokoyamae_ Sew.[540]; they were obtained from the Wealden beds of Sussex, but according to Mr Rufford, who discovered them, the smaller tubers of this species are not found in association with those of _E. Burchardti_. The stems are very narrow and the tubers have a characteristic elliptical form; the species is of little value botanically, but it affords another instance of the common occurrence of these tuberous branches in the Wealden Equisetums.

Similar fossil tubers, on a much larger scale, have been found in association with the Triassic _Equisetites arenaceus_; with _E. Parlatori_ Heer[541], a Tertiary species from Switzerland, and with other Mesozoic and Tertiary stems. _E. Burejensis_[542], described by Heer from the Jurassic rocks of Siberia, bears a close resemblance to the Wealden species.

• • • • •

The description of the above species by no means exhausts the material which is available towards a history of fossil Equisetums. The examples which have been selected may serve to illustrate the kind of specimens that are usually met with, as well as some of the possible sources of error which have to be borne in mind in the description of species.

Such Tertiary species as have been recorded need not be considered; they furnish us with no facts of particular interest from a morphological point of view. The wide distribution of _Equisetites_, especially during the Jurassic period, is one of the most interesting lessons to be learnt from a review of the fossil forms. No doubt a detailed comparison of the several species from different parts of the world would lead us to reduce the number of specific names; and at the same time it would emphasize the apparent identity of fossils which have been described from widely separated latitudes under different names.

Specimens of _Equisetites_ are occasionally found in plant-bearing beds apart from the other members of a Flora; this isolated manner of occurrence suggests that the plant grew in a different station from that occupied by Cycads and other elements of the vegetation[543].

A selection of Triassic and Jurassic species arranged in a tabular form demonstrates the world-wide distribution of this persistent type of plant[544].

B. _Phyllotheca._

The generic name _Phyllotheca_ was proposed by Brongniart[545] in 1828 for some small fossil stems from the Hawkesbury river, near Port Jackson, Australia. The stems of this genus are divided into nodes and internodes and possess leaf-sheaths as in _Equisetum_, but _Phyllotheca_ differs from other Equisetaceous plants in the form of the leaves and in the character of its sporophylls. We may define the genus as follows:—

Plants resembling in habit the recent Equisetums. Stems simple or branched, divided into distinct nodes and internodes, the latter marked by longitudinal ridges and grooves; from the nodes are given off leaf-sheaths consisting of linear-lanceolate uninerved segments coherent basally, but having the form of free narrow teeth for the greater part of their length. The long free teeth are usually spread out in the form of a cup and not adpressed to the stem, the tips of the teeth are often incurved.

The sporangia are borne on peltate sporangiophores attached to the stem between whorls of sterile leaves.

Our knowledge of _Phyllotheca_ is unfortunately far from complete. The chief characteristic of the vegetative shoots consists in the cup-like leaf-sheaths; these are divided up into several linear segments, which differ from the teeth of an _Equisetum_ leaf-sheath in their greater length and in their more open and spreading habit of growth. The large loose sheaths of the fertile shoots of some recent Horse-tails bear a certain resemblance to the sheaths of _Phyllotheca_. The diagnosis of the fertile shoots is founded principally on some Permian specimens of the genus described by Schmalhausen from Russia[546] and redescribed more recently by Solms-Laubach[547]. Prof. Zeiller[548] has, however, lately received some examples of _Phyllotheca_ from the Coal-Measures of Asia Minor which bear strobili like those of the genus _Annularia_, a type which is dealt with in the succeeding chapter. A description of a few species will serve to illustrate the features usually associated with this generic type, as well as to emphasize the unsatisfactory state of our knowledge as to the real significance of such supposed generic characteristics.

There are a few fossil stems from Permian rocks of Siberia, from Jurassic strata in Italy, and from Lower Mesozoic and Permo-Carboniferous beds in South America, South Africa, India and Australia which do not conform in all points to the usually accepted definition of _Equisetites_, and so justify their inclusion in an allied genus. On the other hand there are numerous instances of stems or branches which have been referred to _Phyllotheca_ on insufficient grounds. Our knowledge of this Equisetaceous plant has recently been extended by Zeiller[549], who has recorded its occurrence in the Coal-Measures of Asia Minor associated with typical Upper Carboniferous plants. The same author[550] has also brought forward good evidence for the Permian age of the beds in Siberia and Altai, where _Phyllotheca_ has long been known. It is true that Zigno’s species of the genus occurs in Italian Jurassic rocks, but on the whole it would seem that this genus is rather a Permian than a Jurassic type. The species which Zeiller describes under the name _Phyllotheca Rallii_ from the Coal-Measures of Herakleion (Asia Minor) shows some points of contact with _Annularia_. It is much to be desired, however, that we might learn more as to the reproductive organs of this member of the Equisetales; until we possess a closer acquaintance with the fructification we cannot hope to arrive at any satisfactory conclusion as to the exact position of the genus among the Calamarian and Equisetaceous forms. M. Zeiller[551] informs me that his specimens of _P. Rallii_, which are to be fully described in a forthcoming work, include fossil strobili resembling those of _Annularia radiata_. The verticils of linear leaves fused basally into a sheath agree in appearance with the star-like leaves of _Annularia_, but in _Phyllotheca Rallii_ the segments appear to spread in all directions and are not extended in one plane as in the typical _Annularia_[552].

1. _Phyllotheca deliquescens_ (Göpp.).

In an account of some fossil plants collected by Tchikatcheff in Altai, Göppert[553] describes and figures two imperfect stems of an Equisetum-like plant. Owing to the apparent absence of nodal lines on the surface of the stem the generic name _Anarthrocanna_ is proposed for the fossils; and the manner in which the main axis appears to break up into slender branches suggested the specific name _deliquescens_. Schmalhausen[554] afterwards recognised the generic identity of Göppert’s fragments with the Indian and Australian stems referred to the genus _Phyllotheca_ by McCoy[555] and Bunbury[556].

We may define the species as follows:—

Stem reaching a diameter of 2–3 cm. with internodes as much as 4 cm. long, the surface of which is traversed by longitudinal ridges and grooves which are continuous and not alternate at the nodes. Branches arise in verticils from the nodes. The leaves have the form of funnel-shaped sheaths split up into narrow and spreading linear segments, each of which is traversed by a median vein. The fertile shoot terminates in a loose strobilus bearing alternating whorls of sterile bracts and sporangiophores.

The specimens on which this diagnosis is founded are for the most part fragments of sterile branches. Some of these present the appearance of Calamitean stems in which the ridges and grooves continue in straight lines from one internode to the next. Similar stem-casts have been referred by some writers to the allied genus _Schizoneura_, and it would appear to be a hopeless task to decide with certainty under which generic designation such specimens should be described. The portion of stem shown in fig. 67 affords an example of an Equisetaceous plant, probably in the form of a cast of a hollow pith, which might be referred to either _Phyllotheca_ or _Schizoneura_. The specimen was found in certain South African rocks which are probably of Permo-Carboniferous age[557]. It agrees closely with some stems from India described by Feistmantel[558] as _Schizoneura gondwanensis_, and it also resembles equally closely the Australian specimens referred by Feistmantel[559] to _Phyllotheca australis_ and some stems of _Phyllotheca indica_ figured by Bunbury[560].

The longitudinal ridges and grooves shown in fig. 67 probably represent the broad medullary rays and the projecting wedges of secondary wood surrounding a large hollow pith, as in _Calamites_. In the Calamitean casts the ridges and grooves of each internode usually alternate in position with those of the next, as in _Equisetum_ (fig. 54, A), but in _Phyllotheca_, _Schizoneura_ and _Archaeocalamites_ there is no such regular alternation at the nodes of the internodal vascular strands.

In _Phyllotheca_ and _Schizoneura_ there are no casts of ‘infranodal canals’ below each nodal line, but these are by no means always found in true Calamites. It is therefore practically impossible to determine the generic position of such fossils as that shown in fig. 67 without further evidence than is afforded by leafless casts.

A few examples of _Phyllotheca deliquescens_ have been described by Schmalhausen in which a branch bears clusters of sporangiophores, alternating with verticils of sterile bracts. The sporangiophores appear to have the form of stalked peltate appendages bearing sporangia, very similar to the sporangiophores of _Equisetum_. Solms-Laubach[561] has examined the best of Schmalhausen’s specimens, and a carefully drawn figure of one of the fertile branches is given in his _Fossil Botany_.

The significance of this manner of occurrence of sporangiophores and whorls of sterile bracts on the fertile branch will be better understood after a description of the strobilus of _Calamites_. In _Phyllotheca_ the sporangiophores appear to have been given off in whorls, which were separated from one another by whorls of sterile bracts, whereas in _Equisetum_ there are no sterile appendages associated with the sporangiophores of the strobilus, with the exception of the annulus at the base of the cone. Heer[562] first drew attention to the fact that in _Phyllotheca_ we have a form of strobilus or fertile shoot to a certain extent intermediate in character between _Equisetum_ and _Calamites_.

In abnormal fertile shoots of _Equisetum_, sporophylls occasionally occur above and below a sterile leaf-sheath. Potonié[563] has figured such an example in which an apical strobilus is succeeded at a lower level by a sterile leaf-sheath, and this again by a second cluster of sporophylls. As Potonié points out, this alternation of fertile and sterile members affords an interesting resemblance between _Phyllotheca_ and _Equisetum_. It suggests a partial reversion towards the Calamitean type of strobilus.

2. _Phyllotheca Brongniarti_ Zigno. Fig. 68, A.

This species of _Phyllotheca_ from the Lower Oolite rocks of Italy is known only in the form of sterile branches. The leaves are fused basally into an open cup-like sheath which is dissected into several spreading and incurved linear segments. The internodes are striated longitudinally; they are about 2 mm. in diameter and 10 mm. in length.

The specimen represented in fig. 68, A, was originally described by the Italian palaeobotanist Zigno[564]; it serves to illustrate the points of difference between this genus and the ordinary _Equisetum_. The open and spreading sheaths clasping the nodes and the erect solitary branches give the plant a distinctive appearance.

A. _Phyllotheca Brongniarti_, Zigno. Nat. size. (After Zigno.)
B. _Calamocladus frondosus_, Grand’Eury. (After Grand’Eury.)
Slightly enlarged.
C. _Phyllotheca indica_, Bunb. Part of a leaf-sheath. From a specimen
in the Museum of the Geological Society. Slightly enlarged.]

3. _Phyllotheca indica_ Bunb. and _P. australis_ Brongn. Fig. 68, C.

Sir Charles Bunbury[565] described several imperfect specimens from the Nagpur district of India under this name, but he expressed the opinion that it was not clear to him if the plant was specifically distinct from the _Phyllotheca australis_ Brongn. previously recorded from New South Wales. Feistmantel[566] subsequently described a few other Indian specimens, but did not materially add to our knowledge of the genus. Bunbury’s specimens were obtained from Bharatwádá in Nagpur, in beds belonging to the Damuda series of the Lower Gondwana rocks, usually regarded as of about the same age as the Permian rocks of Europe.

_Phyllotheca indica_ is represented by broken and imperfect fragments of leaf-bearing stems. The species is thus diagnosed by Bunbury:—“Stem branched, furrowed; sheaths lax, somewhat bell-shaped, distinctly striated; leaves narrow linear, with a strong and distinct midrib, widely spreading and often recurved, nearly twice as long as the sheaths.” An examination of the specimens in the Museum of the Geological Society of London, on which this account was based, has led me to the opinion that it is practically impossible to distinguish the Indian examples from _P. australis_ described by Brongniart[567] from New South Wales. The few specimens of the latter species which I have had an opportunity of examining bear out this view. In the smaller branches the axis of _P. indica_ is divided into rather short internodes on which the ridges and grooves are faintly marked. In the larger stems the ridges and grooves are much more prominent, and continuous in direction from one internode to the next; a few branches are given off from the nodes of some of the specimens. The leaves are not very well preserved; they consist of a narrow collar-like basal sheath divided up into numerous, long and narrow segments, which are several times as long as the breadth of the sheath, and not merely twice as long as Bunbury described them. Each leaf-sheath has the form of a very shallow cup-like rim clasping the stem at a node, with long free spreading segments which are often bent back in their distal region. The general habit of the leafy branches appears to be identical with that of _P. australis_ as figured by McCoy.

Prof. Zeiller informs me that in the type-specimen on which Brongniart founded the species, _P. australis_, the sheath appears to be closely applied to the stem with a verticil of narrow spreading segments radiating from its margin. It may be, therefore, that in the Australian form there was not such an open and cup-like sheath as in _P. indica_; but it would be difficult, without better material before us, to feel confidence in any well marked specific distinctions between the Indian and Australian Phyllothecas.

On the broader stems, such as that of fig. 67, we have clearly marked narrow grooves and broader and slightly convex ridges, which present an appearance identical with that of some Calamitean stems. In the specimen figured by Bunbury[568] in his Pl. X, fig. 6, there is a circular depression on the line of the node which represents the impression of the basal end of a branch; on the edges of the node there are indications of two other lateral branches. The nature of this stem-cast points umnistakeably to a woody stem like that of _Calamites_. The precise meaning of the ridges and grooves on the cast is described in the Chapter dealing with Calamitean plants.

[Sidenote: CALAMOCLADUS.]

Grand’Eury[569] in his monograph on the coal-basin of Gard, has recently described under the name of _Calamocladus frondosus_ what he believes to be the leaf-bearing axes of a Calamitean plant. The thicker branches are almost exactly identical in appearance with the broader specimens of _Phyllotheca_. The finer branches of _Calamocladus_ bear cup-like leaf-sheaths which are divided into long and narrow recurved segments (fig. 67, B), precisely as in _Phyllotheca_. These comparisons lead one to the opinion that the _Phyllotheca_ of Australia and India may be a close ally of the Permo-Carboniferous Calamitean plants. The form of the leaf-whorls of _Annularia_ (Calamarian leaf-bearing branches) and of _Calamocladus_ is of the same type as in _Phyllotheca_; the character of the medullary casts is also the same. The nature of the fertile shoot of _Phyllotheca_ described by Schmalhausen from Siberia, with its alternating whorls of sterile and fertile leaves, is another point of agreement between this genus and Calamitean plants. An Equisetaceous species has been described from the Newcastle Coal-Measures of Australia by Etheridge[570] in which there are two forms of leaves, some of which closely resemble those of _Phyllotheca indica_, while others are compared with the sterile bracts of _Cingularia_, a Calamitean genus instituted by Weiss[571].

When we turn to other recorded forms of _Phyllotheca_ many of them appear on examination to have been placed in this genus on unsatisfactory grounds. Heer figures several stem fragments from the Jurassic rocks of Siberia as _P. Sibirica_ Heer[572], and it was the resemblance between this form and the English _Equisetites lateralis_ which led to the substitution of _Phyllotheca_ for _Equisetites_ in the latter species. Without examining Heer’s material it is impossible to criticise his conclusions with any completeness, but several of his specimens, appear to possess leaf-sheaths more like those of _Equisetum_ than of _Phyllotheca_.

The frequent occurrence of isolated diaphragms and the comparatively long acuminate teeth of the leaf-sheath afford obvious points of resemblance to _Equisetites lateralis_. Some of the examples figured by Heer appear to be stem fragments, with numerous long and narrow filiform leaves different in appearance from those of other specimens which he figures. It may be that some of the less distinct pieces of stems are badly torn specimens in which the internodes have been divided into filiform threads. Heer also figures a fertile axis associated with the sterile stems, and this does not, as Heer admits, show the alternating sterile bracts such as Schmalhausen has described. So far as it is possible to judge from an examination of Heer’s figures and a few specimens from Siberia in the British Museum—and this is by no means a safe basis on which to found definite opinions—there appears to be little evidence in favour of separating the fossils described as _Phyllotheca Sibirica_ from _Equisetites_. This Siberian form may indeed be specifically identical with _Equisetites lateralis_ Phill.

Various species of _Phyllotheca_ have been described from Jurassic and Upper Palaeozoic rocks in Australia. Some of these possess cup-like leaf-sheaths, and in the case of the thicker specimens they show continuous ridges and grooves on the internodes, as well as a habit of branching similar to that in some of the Italian Phyllothecas. In some of the stems it is however difficult to recognise any characters which justify the use of the term _Phyllotheca_. A fragment figured by Tenison-Woods[573] as a new species of _Phyllotheca_, _P. carnosa_, from Ipswich, Queensland, affords an example of the worthless material on which species have not infrequently been founded. The author of the species describes his single specimen as a “faint impression”; the figure accompanying his description suggests a fragment of some coniferous branch, as Feistmantel has pointed out in his monograph on Australian plants.

It is important that a thorough comparative examination should be made of the various fossil Phyllothecas with a view to determine their scientific value, and to discover how far the separation of _Phyllotheca_ and _Equisetites_ is legitimate in each case. There is too often a tendency to allow geographical distribution to decide the adoption of a particular generic name, and this seems to have been especially the case as regards several Mesozoic and Palaeozoic Southern Hemisphere plants.

The geological and geographical range of _Phyllotheca_ is a question of considerable interest, but as already pointed out it is desirable to carefully examine the various records of the genus before attempting to generalise as to the range of the species. _Phyllotheca_ is often spoken of as a characteristic member of the _Glossopteris_ Flora of the Southern Hemisphere, and its geological age is usually considered to be Mesozoic rather than Palaeozoic.

C. _Schizoneura._

The plants included under this genus were originally designated by Brongniart[574] _Convallarites_ and classed as Monocotyledons. Some years later Schimper and Mougeot[575] had the opportunity of examining more perfect material from the Bunter beds of the Vosges, and proposed the new name _Schizoneura_ in place of Brongniart’s term, on the grounds that the specimens were in all probability portions of Equisetaceous stems, and not Monocotyledons. Our knowledge of this genus is very limited, but the characteristics are on the whole better defined than in the case of _Phyllotheca_. The following diagnosis illustrates the chief features of _Schizoneura_.

Hollow stems with nodes and internodes as in _Equisetum_; the surface of the internodes is traversed by regular ridges and grooves, which are continuous and not alternate in their course from one internode to the next. The leaf-sheaths are large and consist of several coherent segments; the sheaths are usually split into two or more elongate ovate lobes, and each lobe contains more than one vein. Fertile shoots are unknown.

Two of the best known and most satisfactory species are _Schizoneura gondwanensis_ Feist. and _S. paradoxa_ Schimp. and Moug.

_Schizoneura gondwanensis_ Feist. Fig. 69, A and B.

This species is represented by numerous specimens from the Lower Gondwana rocks of India[576]; it is characterised by narrow articulated stems which bear large leaf-sheaths at the nodes. The sheaths may have the form of two large and spreading elongate-oval lobes, each of which is traversed by several veins (fig. 69, B), or the lobes may be further dissected into long linear single-veined segments, as in fig. 69, A. It is supposed that in the young condition each node bears a leaf-sheath consisting of laterally coherent segments which, as development proceeds, split into two or more lobes. Feistmantel records this species from the Talchir, Damuda and Panchet divisions of the Lower Gondwana series of India; these divisions are regarded as equivalent to the Permo-Carboniferous and Triassic rocks of Europe. The two specimens shown in fig. 69 are from the Lower Gondwana rocks of the Raniganj Coal-field, India.

As already pointed out[577], some of the specimens of flat and broader stems referred by Feistmantel to _Schizoneura_ are identical in appearance with stems which have been described from India and elsewhere as species of _Phyllotheca_.

There are a few specimens of _S. gondwanensis_ in the British Museum, but the genus is poorly represented in European collections.

A similar plant was described in 1844 by Schimper and Mougeot[578] from the Bunter rocks of the Vosges as _Schizoneura paradoxa_. This species bears a very close resemblance to the Indian forms, and indeed it is difficult to point to any distinction of taxonomic importance. Feistmantel considers that the European plant has rather fewer segments in the leaf-sheaths, and that the Indian plant had somewhat stronger stems. Both of these differences are such as might easily be found on branches of the same species. It is, however, interesting to notice the very close resemblance between the Lower Trias European plant and the somewhat older member of the _Glossopteris_ flora recorded from India and other regions, which probably once formed part of that Southern Hemisphere Continent which is known as Gondwana Land[579].