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genera are retained, and an alphabetical list is given, with references to the modern genera which form the subject of the present work, and of the analytical and synoptical tables.

The following brief explanation of the principles of arrangement employed in this treatise must suffice. The artificial classification of the former edition had almost exclusive reference to the structure of the peristome, in conjunction with the form of the calyptra. The absence of a peristome was regarded as a positive character, and an essential difference was also assumed to exist between mosses with a single and those with a double peristome. The natural arrangement combines into one generic group all those species which have a stronger mutual resemblance of structure, in all parts, than to those of any other group; the sum of characters, and not any single character exclusively, being taken into account. The structure of the peristome is indeed still regarded as of primary importance; but when absent, or only partially developed, as in the case of Encalypta, &c., the deviation is regarded as nonessential; hence, it is believed that some of the genera of the Bryologia Europea deferentially admitted into this work require to be remodelled. The form of the calyptra is generally, but not invariably, of importance. The texture of the leaves may not always have received due attention in this work. The insertion of the leaves, in those species where they are truly distichous, appears to constitute an essential character ; thus the genus Fissidens is properly separated from Dicranum, potwithstanding the great similarity of the peristome. It seems still very desirable to preserve the acrocarpous and pleurocarpous mosses as separate groups, notwithstanding the existence of cladocarpous species, which form a connecting link, as in Fissidens, and although there are plausible grounds for the admission of Anectangium as a pleurocarpous section of Zygodon.

In the determination of species, it will be seen that great stress is laid on the inflorescence. This feature is somewhat new and strange to British Bryologists, and may prove a stumbling-block to the learner, who is strongly advised not to shrink from the necessary work of dissection under the microscope. The species, in many instances, depend much on this character for a compendious and satisfactory definition, and long experience has shown that the distinctions thus obtained are permanent and essential, being accompanied by structural peculiarities less obvious, and therefore less available in a verbal definition of the species.

To facilitate the entrance of the learner into this study, a familiar example is here given of the structure and arrangement of the inflorescence and fructification.

If Funaria hygrometrica (common on almost every bank, and easily recognised) be examined in autumn, or early in winter, previous to the appearance of young fruitstalks, reddish stellate flowers will be found at the tops of the young shoots or stems. These are the barren or male flowers, and, on dissection in water, are found to consist of a cluster of oblong bladder-like vesicles (antheridia), mixed with jointed pellucid filaments (paraphyses), and surrounded by several rows of spreading leaves constituting the perigonium. The antheridia are at first filled with a semigelatinous mass of loose cellular tissue, of which each cellule contains a spermatozoid, composed of a spiral fibre with a very small oval or roundish corpuscle attached thereto, usually near the middle of the spire. At the period of maturity the antheridia burst at the top, and the contents escape with more or less of explosive action. Soon afterwards, the spermatozoids begin to gyrate rapidly within the cells, and at length, escaping from confinement, move about (in the water) in various directions. This motion is often continued for several hours. The empty antheridia are visible long afterwards, and assume a reddish-brown colour.

At the same season, and on the same individual, the fertile flower may be easily found by dissection at the

apex branch. The fertile flower consists of slender flask-shaped bodies (archegonia), mixed with jointed filaments (paraphyses), and surrounded by a cluster of erect leaves, which at length constitute the perichætium. The archegonia are somewhat longer and considerably more slender than the antheridia, and are filiform, except towards the base, where they are slightly tumid, and at the apex, where they are slightly expanded : a central canal extends from the apex to the swollen cavity near the base, where is lodged a roundish vesicle (the germ of the future fruitstalk and capsule); and in general only one of the archegonia comes to perfection, the rest being ultimately found in an abortive state attached to its base. The perfect archegonium soon becomes enlarged and distended

of a young by the increase in bulk of the contained vesicle, and is at length torn asunder at an horizontal fissure near the base, the upper portion being converted into the calyptra, and the base into the vaginula. The rudimentary vesicle is now converted into a fruitstalk, having its tapering base inserted and firmly fixed in the vaginula, and its apex sheathed by the young calyptra. When the fruitstalk has attained its full length, and not before, its apex swells and becomes changed into the capsule. The capsule contains a central column (columella), around which the spores (analogous to seeds) are generated within a membranous sac (sporular sac), which lines the cavity formed by the external walls of the capsule. The mouth of the capsule is closed up at first by the lid or operculum, and an intermediate coloured ring (annulus), composed of large cellular tissue, which, by its hygrometric action, causes the lid to fall off from the ripe capsule, disclosing the beautiful peristome, whose hygrometric action regulates the escape of the spores. The peristome is double, the outer one being a continuation of the inner wall of the capsule (called the thecal membrane), and the inner one a continuation of the sporular

At this period the short branch which bore the fertile flower is much elongated, and overtops and conceals the barren flower now apparently at the base of the stem. In this example, the two kinds of flowers are separated; but in many mosses the antheridia and archegonia are intermixed in the same flower, e.g. in Bryum cernuum and other species, common on walls, and formerly confounded with B. cæspiticium, but easily distinguished from that species by means of the inflorescence. Illustrations of the antheridia and archegonia, magnified forty times, are given at Tab. LI. (Mnium subglobosum), and Tab. XLIX. (Bryum intermedium).

Of the function of the antheridia nothing is known by actual observation; but it is a well established fact that, wherever they are absent, fruit is never produced from the archegonia. The dioicous species of Hypna are usually destitute of capsules from this cause, or from the absence of archegonia, in any given district; and a little pains bestowed in examining the nature of the inflorescence may often save much useless toil in the search for fruit, or may lead to its discovery.

The species described in this work, exclusive of some whose nativity as British is very doubtful, amount to 444, of which

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only 290 are described in the Second Edition of Musc. Brit. Nearly all the newly-described species have been illustrated by figures, and the illustrations which originally appeared in Musc. Brit., and which have been transferred to the present work, have been corrected when necessary. In most cases the species of Hypnum are represented only by magnified figures of the leaves; otherwise the price of the book must have been much increased by the additional number of plates.

Of the uses of Mosses in the economy of creation, very little is known; but they are often the necessary precursors of a higher order of vegetables, for which they prepare a soil, by retaining amongst their matted branches the drifting sand and dust, in places which would otherwise remain bare and sterile. They afford refuge in winter, and food as well as lodgment in summer, to innumerable insects. In a living state they are useful as package for the transmission of growing plants, not being apt to grow mouldy, and retaining their vitality and moisture for a long period. Many species of Hypnum when dried are highly elastic, and suitable for packing delicate and fragile articles ; and a pillow stuffed with Hypnum will explain, if it may not have originally suggested, the name from the Greek word signifying sleep. To the traveller in the dense and trackless forests of North America, they are pretty sure guides to the points of the compass, growing on the northern sides of the trunks of trees, where they find most shade and moisture.

For the sake of brevity, references to the pages of the authors cited have been generally omitted, and only the figures indicated; and the figures of Dillenius' Historia Muscorum, indiscriminately subjoined to names subsequently given by other authors, are cited without the names or descriptive phrases. In almost every case where Smith, English Botany, is mentioned, the Flora Britannica of the same author must be understood as included.

The geographical distribution of mosses will more properly form the subject of a separate work, our present object being to furnish the student, in as compendious a form as possible, with the means of identifying the indigenous species of a tribe of plants often so diminutive in size and so unpretending in colour as to escape the notice of any but an educated eye, but which, when examined by the aid of the microscope, display such exquisite symmetry and beauty as to call forth the ad. miration and delight of the beholder ; – delight, not in the outward senses only; for, as good old Gerarde truly says, “the principal delight is in the mind, singularly enriched with the knowledge of these visible things, setting forth to us the invisible wisdom and admirable workmanship of Almighty God;" and recalling the fervid exclamation of the Psalmist,“ O Lord, how manifold are thy works! in wisdom hast thou made them all : the earth is full of thy riches."

Our thankful acknowledgments are tendered to those kind friends who have supplied materials for this work, and whose names appear in connection with their discoveries and communications.

ADVERTISEMENT.

ILLUSTRATIVE sets of specimens of about 400 of the species described in this work may be had at the rate of twenty shillings per hundred. The specimens are generally in good condition, it having been the endeavour of the collector, for many years past, to obtain them with fructification at the proper season of maturity. Address, W. Wilson, Manchester Road, Warrington.

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