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This hypothesis, M. Naudin calls 'toute gratuite.' His own explanation does not indicate that he possesses any surer key, and Mr. Darwin's theory is not adverted to. The only case, and that a doubtful one, which has occurred to M. Naudin, in which hybrid characters appear tending to become confirmed, is that of Egilops, said to have originated from a cross between E. ovata and common wheat. This has been cultivated in the garden of the Museum for a dozen years, without appreciable change.

M. Godron, who, as we have stated, holds that hybrids are constantly sterile, regards the Egilops, referred to by M. Naudin (the E. speltaeformis of Jordan), as a 'quarteron,' resulting from the fertilisation of Æ. triticoides by the pollen of wheat. E. triticoides he considers to be a sterile hybrid between Æ. ovata and common wheat.

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M. Naudin devotes a chapter to a discussion of the relations of races and varieties, with a view especially to the distinctions which are generally made between hybrids and mongrels (métis). "La délimitation des espèces"-he says "est. ... entièrement facultative; on les fait plus larges ou plus étroites, suivant l'importance qu'on donne aux ressemblances et aux diffèrences des divers groupes d'individus mis en regard l'un de l'autre, et ces appréciations varient suivant les hommes, les temps, et les phases de la science." "Suit il de là que les mots race et variété doivent être bannis de la science? Non, sans doute, car ils sont commodes pour désigner les faibles espèces qu'on ne veut pas enregistrer parmi les espèces officielles, mais il convient de leur donner leur vraie signification qui est absolument la même que celle d'espèce proprement dite, et de voir dans les formes désignées par ces mots des unités d'une faible valeur qu'on peut négliger sans inconvénient pour la science." And, finally, "Il suit de tout ce qui précède que l'application des mots hybride et métis est déterminée par le rang qu'on assignera aux formes dont le croisement a produit les formes mixtes qu'il s'agit de dénommer, c'est-àdire entièrement livrée au jugement et au tact du nomenclateur."

IX. THE LIGNITE FORMATION OF BOVEY TRACEY.

ON THE LIGNITE FORMATION OF BOVEY TRACEY, DEVONSHIRE. By William Pengelly, F.R.S., &c., and the Rev. Oswald Heer, Ph.D., M.D., &c.

Two valuable and carefully prepared Memoirs, read before the Royal Society in November, 1861,-one entitled, "The Lignites and

Clays of Bovey Tracey," by Mr. Pengelly, the other "On the Fossil Flora of Bovey Tracey," by Dr. Heer, of Zurich, are now in the hands of the Fellows. Through the liberality of Miss Burdett Coutts, a number of additional copies have been separately bound, prefaced by a general historical introduction by Mr. Pengelly, and distributed to Institutions and individuals likely to be interested in the work.

The chief interest of these Memoirs consists in the very full and detailed account of the numerous beds forming the Bovey deposit, and in the satisfactory settlement of the geological age of the lignites, and also of the gravelly or white-clay bed overlying, unconformably, the lignite strata. We confine our remarks to Professor Heer's account of the Fossil Flora of Bovey Tracey, which appears to have been drawn up with great pains.

The Bovey lignite deposits occupy a basin immediately bordering upon the granitic and metamorphic rocks of Dartmoor; detritus derived from which is interstratified with the lignites. The spot where the sections have been made, is toward the north-western extremity of the basin, near the village of Bovey Tracey, at a pit from which lignite was formerly worked for use in an adjoining pottery. Bovey Tracey is about eleven miles N.W. from Torquay.

The lignites occur in numerous beds (about thirty), of varying thickness, alternating with bands of the Dartmoor detritus referred to above. Of these lignite beds, Mr. Pengelly states the twenty-sixth to be the most interesting, from the abundance of fossil remains which it affords. Altogether, forty-nine "species" have been added to our Fossil Flora by the recent explorations at Bovey, and of these, twenty-six are now first described by Professor Heer. Four or five species are described from the clay overlying the lignite deposit. The lignite remains are "undoubtedly miocene," while the few impressions found in the unconformable clay-beds are of much more recent date, and are assigned to the "diluvium."

With regard, first, to the Lignite remains.

Twenty-one of the fifty species occur in miocene beds on the Continent, according to Professor Heer. Nineteen species are common to Bovey and the Aquitanian stage of the lower miocene, eleven being common to Bovey and the Swiss Aquitanian beds. Several of the Bovey species occur also in the Provence tertiary beds of Manosque, where, as at Bovey, "the most frequent fern is Pecopteris lignitum.” Heer points out that none of the Bovey species, and only two of the genera-Sequoia and Quercus, occur in the Iceland miocene beds. A

few genera and one species are common to Bovey and to the eocene beds of the Isle of Wight.

The principal mass of the subtropical vegetation of which we have the débris preserved to us in the Bovey Tracey lignites consisted of, first and foremost, a Conifer allied to Wellingtonia, and referred to the genus Sequoia; a genus (like Wellingtonia which is nearly allied to it), now confined to western North America. As the remains differ somewhat from those of other supposed Sequoias found abundantly in the miocene of Europe, the Bovey species has been distinguished as a new species under the name of S. Couttsic, in honour of the munificent lady to whom the explorers have been indebted for the pecuniary means essential to the success of their work. S. Couttsic and Pecopteris lignitum, the latter a widely distributed fern during the Tertiary epoch, are the commonest plants of Bovey, and " contribute the greatest amount of lignite." Both branches, cones and seeds of the Sequoia have been found, so that the material for comparison with recent forms has been unusually good, although by no means sufficient to enable us to speak of the determination with absolute certainty. The fossil appears to us to be quite as nearly allied to Glyptostrobus of Eastern Asia, as to Sequoia, especially in the fruit, and in the radiating sulci and apiculus of the peltate scales forming the more or less globose cones. The very trivial difference in the form and direction of the leaves, which are subfalcate in the Bovey tree, and straight or "somewhat curved outwards" in Glyptostrobus, is of no weight whatever in a generic point of view.

Next in abundance to the Sequoia,' are two trees referred to the genus Cinnamon (Cinnamomum), and an evergreen Oak (Quercus Lyelli); the latter "like those which are seen in Mexico." But, surely, also elsewhere than in Mexico! We could quite as easily match the Bovey Oak with East Asiatic or Himalayan species as with Mexican, but then the former do not require to pay toll on the Atlantis bridge; in which undertaking, as every one knows, Professor Heer has some capital invested. Quercus lanceafolia of the Himalaya and Q. Harlandi of Hong Kong, are near to Q. Lyelli, as represented in the plates of Professor Heer's memoir.

The tripli-nerved Laurels should certainly not be referred to Cinnamomum. They appear to us more nearly allied to Litsea. The inflorescence of the true Cinnamons is usually lax, branching, and almost panicled.

Less frequent than the foregoing, in the ancient forest of the

Bovey slopes, were 'evergreen Figs,' of which three new "species" are described, though upon sufficiently wretched data; two Anonas, and Gardenia Wetzleri. The identification of the two last-named genera is simply worthless. With regard to the so-called Gardenia, the seeds, arranged apparently in the same relative position as in the fruit, have been met with in the Bovey lignites. It is by no means improbable that they belong to the same species as the widely distributed fossil found near Königsberg, and in the brown-coal of the Rhön, &c. with which Professor Heer identifies them. The seeds are more like those of an Amomum than of a Gardenia; in some Amomums the tissue of the pulpy aril is frequently found spirally wound around the seeds, in a manner very similar to the marking or sculpture on those figured by Professor Heer. How far the pulp, in drying around the seeds of Amomum, may leave a spiral tracing upon their surface, we are unable to say.

A number of pectinate, parallel, or slightly divergent prickles, arranged usually in threes, are referred to a palm, while three seeds, about the size of common grape 'stones,' are referred to two new species of vine, viz. Vitis Hookeri, based upon one seed, which "cannot be mistaken," and V. britannica upon the other two; the latter determination is acknowledged not to be "quite certain." Much doubt attends most of the remaining identifications of the Bovey fossil Phanerogamia, and especially that of the Nyssas and the Monopetalous genera. No fewer than four species of the United States genus Nyssa are described, one of them being referred to the same species with some fruit-stones found in the Salzhausen miocene beds.

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Four species of Fern are made out, including the Pecopteris lignitum referred to above. Large masses, covered with the remains of the bases of fronds or leaves, are assigned to this species, which Professor Heer says, seems to have formed trees of imposing grandeur." With respect to these masses (rhizomes, according to Professor Heer), of which we have had the opportunity of inspecting one or two, we may remark, that some of our best Pteridologists laugh at the idea of their being Fern remains at all.

The minute fruits or seeds described by Dr. Hooker under the name of Folliculites minutulus, in the Journal of the Geological Society (1855), and which he thought might belong to some Cryptogam, Professor Heer ranges under Carpolithes. He thinks they are fruits and not seeds, but cannot suggest any probable affinity;

which, from their very wide dispersion in the miocene formation, is to be regretted. They are very fully and accurately described by Dr. Hooker, and botanists will do well to bear them in mind.

In the following list we give a summary of the Natural Orders to which the Bovey Fossils have been referred by Professor Heer, and the number of genera of each Order. Those Natural Orders which we believe may be accepted as very probable determinations are in small capitals; those which appear to us little or no better than mere guesses are in italics.

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With regard to the few impressions found in the white clay over

lying the lignite :

Professor Heer refers them to Willow (Salix) and Birch (Betula); of the former there appear to be two or three species, including perhaps S. cinerea, and perhaps, also, S. repens. The Birch leaves much resemble those of Betula nana, to which Professor Heer refers them. This Birch is a northern low shrub, which at the present period has no well authenticated station, to our knowledge, south of the border, and this evidence of its occurrence in Devonshire during the glacial period is of much interest.

X.-DECAISNE ON THE VARIABILITY OF SPECIES.

DE LA VARIABILITÉ DANS L'ESPÈCE DU POIRIER; RÉSULTAT D'EXPÉRIENCES FAITES AU MUSEUM D'HISTOIRE NATURELLE DE 1853 à 1862 INCLUSIVEMENT. Par M. Decaisne. From the Comptus rendus des séances de l'Académie des Sciences, Vol. lvii. (Session of July 6th, 1863.)

THIS is an important contribution to the investigation of the difficult question of the variability of species, and the high standing of the author as a sound philosophical botanist, and, at the same time, as an accurate observer and careful experimentalist, gives great weight to the conclusions he arrives at, on a subject which excites so much

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