The most curious resemblance to the forms of art to be found among the bivalves is presented by the shells of the Ark tribe, distinguished by having a long horizontal hinge furnished with tiny teeth. The Arca Nox, when stripped of its mossy epidermis, is so exactly like the hull of a man-of-war that it might almost be taken as a model.

NOAH'S ARK
(Arca tetragona).

An interesting race of Engliish shells are the Pectens or Scallops. One valve is perfectly flat, the other orbed, and rayed longitudinally with beautiful markings in all shades of red, purple, orange, and white. The Pecten Jacobaea is the Scallop of St. James brought home by pilgrims, and often seen in coats of arms. Lately, however, the capabilities of the Avicula Margaritifera for being sculptured have led to its being the shell which the peasants of Bethlehem carve with rude figures, and sell to the visitors to that holy spot. But it is to the connection of St. James with the Scallop-originally gathered on the Spanish coast, on the way to his shrine at Compostella-that the little London boys' habit of erecting a grotto of oyster shells is due, since it was once, no doubt, intended to represent his shrine.

The connections of the Pecten branch out into the beautiful Spondylus, foliated and thorned all over the ribs of its upper valve, with the lower tight grown to a rock; and then to the Anomia, whose very name is in Greek an allusion to its shapelessness, a thin transparent shell, whose flat lower valve, with a round hole through it, is fastened tight down to some parasite-enduring shell. The hole has a stopper or operculum, which holds hard to the supporter at one hand, and on the other grows from the chief interior muscle of the animal. The Anomia is very thin; but the Placuna, its Chinese relative, is almost semi-transparent, and grows to so large a size that it is even used by the poorer Chinese to glaze their windows.

They are the next link to the Oysters, those rude pearl-lined shells that contain the mollusk for which England was famous even under the Roman empire. But of the statistics of oyster-beds our readers have no desire to hear at present, though it may be interesting to them to know that London stands on great masses of the fossil oyster-beds of elder years. The Oysters and their subdivisions are the very last of the great class of ACEPHALE, from which we proceed to the last division of mollusca, the Brachiopoda, or Arm-footed; not that they have a foot, but cilia or arms stretching from their mantle are the derivation of

their name. They generally have bivalve shells, with a hole through the upper valve, and a muscle coming out through it to anchor them to the rock. They are very old-world beings: like the Cephalopoda, their reign was in past ages; only a few linger on the surface of the earth, as if to serve as keys to their dead forefathers, of whom there are many more species buried in the soil than there are of existing representatives.

LAMP SHELL.

The Terebratula, or Lamp Shell, is one of these. It is so called because its upper valve projects beyond the lower, and is perforated just like a classical lamp. Where the wick would come, out protruded its strong muscle, by which it rode at anchor all along the shores of the seas that are now chalk hills, in which multitudes may be found imbedded. Some of these shells, recent as well as fossil, contain curious and regularly curved processes of shelly matter to which the animal was attached, very unlike the ordinarily empty bivalves of the ACEPHALA. The very premier of the whole race, the existing animal whose genealogy is the very oldest of all on this earth, is the Lingula, a little spoon-shaped shell with a Brachiopod inhabitant. His remains, found in the lowest beds of the Silurian strata, are the very first dawnings of animal existence on the earth, the earliest indication of any organic life in our globe. Thenceforth the remains of living beings thicken on the geologist; but the Lingula, the pioneer of life, never fails in every era, and still it lives, deep burrowing in beds of sand, the humblest, if the longest descended, of all the organic existences of creation.

We hope we have said enough to show that Conchology may be a most interesting study, and in its union with Palæontology, it will present ever new and ever old interests.

As to the means of study, a book giving general ideas should first be read. Sowerby's "Popular History of Mollusca," one of Lovell Reeves's pretty Natural History series, is a fair one. So also is Agnes Catlow's "Conchology." Or there are two large quarto volumes of Reeves's, and a beautiful "Manuel Conchologique," par L. C. Chenu, which we have here largely used, and which contains fossil as well as recent shells; the illustrations beautiful, and the price only 25 francs.

After general notions of classification are gained, the special branches come under consideration. Turton's is the largest book of exclusively British shells, which gives figures of all. Another "British Conchology," by Miss Roberts, is in Lovell Reeves's list. "Common Shells of the Sea Shore," by the Rev. J. G. Wood, will be helpful on a sea-side visit; and the S. P. C. K. has such another by Gosse. Fossils may be found in the volume of Geology in "Bohn's Library," now in the hands of Messrs. Bell and Daldy. If you confine yourself to some one genus, you might be able to purchase one of Lovell Reeves's splendid monographs, with figures of all the species; but in general the wisest way, which best feeds the intelligence, is to study the general subject as much as possible from books fairly within the attainment of your purse, collect what you have some chance of collecting with your own hands (complete collections sorted at scientific shops are miserable

encumbrances and hindrances), learn to classify and understand the general position of your specimens; and then, when the opportunity offers of consulting a grand book, or visiting a museum, you will know how and where to look and learn, you will carry home names to your own specimens needing them, and you will see sights, not as gape-seed, but as a study.

And it will be your own fault if the loveliness and adaptation of these palaces of the waters do not aid you to think of the beneficence of their Maker.

SEAWEEDS.

There was a time, and not very long ago, when Seaweeds were the most despised of vegetable life, when professors of botany ignored them, tossed them aside as children's playthings, and only mentioned them as lowest in the scale of Creation, if not absolutely noxious.

The epicure found out, however, that one seaweed made an appetizing sauce: the Englishman calls it laver, the Irishman sloke, the Scotchman slaak, and the scientific man Porphyra; but all agree in dressing it with lemon-juice, spices, and butter, and like it well.

The poorer class of Highlanders and Irish eat the seaweed called Dulse, both as food and medicine; for, like all plants, seaweed is made up of millions of small sacs or cells containing the varied substances it draws from sea-water and sea-air, one of the most important of which is iodine, a specific in all cases of scorbutic and glandular affections.

There is a common saying in Scotland, "He who eats of the dulse of Guerdie and drinks of the wells of Kildingie will escape all maladies except black death."

They prepare it thus in Ireland: First they wash it well in fresh water, and expose it to dry, when it gives out a white powdery substance, which is sweet and palatable, and covers the whole plant. Then they pack it in casks and keep it from the air; and thus preserved, it is ready to be eaten either in this state, with fish and butter, or, according to the practice of richer people, boiled in milk and mixed with a little flour of rye. This powdery substance is mannite, abundant on many of our seaweeds.

Cattle are very fond of dulse, and sheep will wander away dangerously far at low water in search of it. From this circumstance they call it in Norway sousoell, or sheeps'-weed.

The common brown seaweed fringing the rocks from highest to lowest tide is eaten with relish by Highland cows.

The most of us know how excellent for invalids is jelly made from the carrageen or Irish moss. It abounds on all our coasts as Chondrus Crispus - sold at one time as high as 2s. 6d. per lb., because it was a fashionable dish for invalids. No seaweed, however, is more useful and interesting than the very brown common seaweed, that is passed by as useless for the album, and of no beauty whatever; and yet its fructification is of the highest order,

and its importance to the agriculturist so great as to render it very precious in the Channel Islands, Scotland, and Ireland.

The basis of all our classification in Natural History is the fructification. The Creator Himself has so outlined His plan: "The herb yielding seed, and the fruit tree yielding fruit after its kind, whose seed is in itself after its kind." The trees of the forest, the flowers of the field, are not more surely classed by their blossoms and their fruit than are these pretty lowly seaweeds. It makes all the difference too in a mounted specimen-Plocamium for instance-whether it be in fruit or not.

Not only has a seaweed fruit, but on many species there are two kinds of fructification, and on one at least, the Fucus, is recognized the perfect form of vegetable life. You will discover the ordinary forms of fruit with a simple lens, but very little of their great beauty and delicate texture without a microscope. It may be scarcely credible that a most abundant, dark, unlovely weed, called Polysiphonia, is full of little berries, called ceramidia, urn-shaped, transparent, as if fashioned of delicate net-work, containing oblong brown or crimson seeds, whilst another plant close by it bears long pods containing masses of four seeds, or spores, called tetraspores.

If you have a microscope and examine your seaweed intelligently, always take a very small piece and place it on a glass slide with a drop of water, and a thin bit of glass over that again, else you will not be able to see what I describe. Use a low power a 2-inch object-glass is the best; then, if you possess higher powers, use them one by one: the more you investigate the more you will find to astonish and delight you. Minute and unsuspected forms of Algae or seaweed parasitic on the larger ones, and so wholly microscopic as to be classed apart, and called Diatomace, have long been a source of wonder and deep interest to scientific observers: the variety in form, the beauty of their markings it is impossible to conceive without having seen

them.

We dabble in the cool, clear tide-pools, and scarcely know what we take up: there is a world of life in each. The speckled prawn is balancing himself, and waving to and fro his sensitive feelers, springing away under the rich foliage that conceals his hiding place; and the small blenny darts like a lightning-flash from cranny to crevice, the fear and the dread of man upon it. On the green Ulva creeps the lovely little slug-a bright green spotted with white called Acteon viridis, and on darker seaweeds the great purplish sea-hare. Sea-spiders lurk amid the Coralline; and as we gather a bunch of seaweed, we shake out dozens of a pretty little snail called Rissoa, besides gathering, if we please, bright yellow nerits, the commonest sea-snail of our coast. All these force themselves on the notice of the seaweed gatherer, as we scramble over the rocks, and pause to consider where we shall begin. I advise taking a little of everything-not much, for seaweeds soon spoil in waiting to be mounted-and naming each specimen as they are decided by reference to the following Synopsis of Tribes; for, however much the indolent mind may dislike scientific names and classification, it will be found quite impossible to learn any part of Creation without some effort towards both; and the pleasure of collecting is increased tenfold by a knowledge of

the order and the rank each little weed holds in its tiny tide-pool. There is, first of all, the division of colour-red, orange, and green; within this, again, the rising scale of honour in the manner of reproduction, from the simplicity of the green seaweeds to the complexity of the lately-known Fucus. The number of genera, or groups containing varied individuals, is 10; the species as yet detected on the British coast may be about 380. Of these the green seaweeds abound near high-water mark, and have little variety, with the exception of Cladophore, which contain twenty species: they are very beautiful when properly laid out in a seaweed album.

SYNOPSIS OF SEAWEED TRIBES.

They are divided into three great classes-the OLIVE, the RED, and the GREEN SEAWEEDS.

OLIVE GREEN, OR MELANOSPERMEÆ. (Marine plants of an olive green or olive brown colour.)

Fructification.-Monacious or diæcious. Spores either external or contained, singly or in groups, in proper conceptacles. Antheridia (transparent cells) with active small bodies moving by means of vibratile hairs or cilia. Seaweeds of an olive brown or blackish-green colour

1

2

3

4

5

Seaweeds of an olive green or yellowish-green colour} Fucacex.

Fronds membranaceous, inarticulate.

Fronds articulate.

(Spores external, borne on jointed filaments

Spores on the surface of the frond

Sporochnacee.

Spores covering the whole of the frond, or in ill-defined d} Laminariacex.

patches

Spores grouped together in well-defined spots or lines-Dictyotaceæ.
Fronds composed of articulate filaments interlaced to-

gether. Spores immersed

Co-Chordariacex.

Fronds filiform, jointed. Spores external-Ectocarpacex.

GENERA OF THE FUCUS TRIBE.

HALIDRYS-Air-vessels long, pod-shaped.

CYSTOSEIRA-Air-vessels in the branches; receptacles small. PYCNOPHYCUS-Root composed of branching fibres; receptacles cellular. FUCUS-Root a round or flattened disk; receptacles large, filled with mucus, traversed by jointed threads.

HIMANTHALIA-Frond round, small, and cup-shaped; receptacles resembling fronds, very long, repeatedly forked.

GENERA OF THE SPOROCHNUS TRIBE.

FAMILY I., OF THE ARTHROCLADIA,
With their spores attached to slender filaments.

DESMARESTIA-Frond solid, either filiform or flat, distichously branched. ARTHROCLADIA-Frond cylindrical, furnished with whorls of small slender jointed filaments.