bottom of the water. The only difference between larva and nympha is that the latter has sheaths for the wings, which are rolled or crumpled up inside them. The banks of rivers may often be seen to be completely riddled by these larvæ, which tunnel for themselves tubular galleries in the mud to the depth of four or five inches. The larvæ of some other members of the Ephemeridæ, instead of living under the sand, or in tubular galleries, swim from place to place, as in the genus Cloë, while others crawl on the ground and on aquatic plants. The abdomen of the larva and nympha of Ephemera vulgata is bordered on either side by a row of gills which, by their constant motion, serve to draw fresh currents of water to oxygenate the blood. Each gill consists of two large tracheal trunks, in which smaller air vessels ramify in all directions (Fig. N). In the imago state the whole respiratory organization is changed, the tracheal trunks or gills are cast aside, and the insect now breathes by means of stigmata.

The dissection of the insect is a matter of some difficulty, owing to the extreme delicacy of the organs. The alimentary canal consists of a short oesophagus, stomach with rudimentary hepatic vessels, and intestine with its numerous renal or urinary vessels.

The stomach (ventriculus) is long and cylindrical, marked by several constrictions. In the sub-imago state it is surrounded by a distinct mass of secreting vessels of a very irregular form, which contain numerous curious bodies, circular in form, marked by concentric lines. These concentric lines seem to show that the bodies are formed of fine threads coiled one over the other, the thick end, in shape something like the head of a snake, being free (Figs. I, J, K).

In the imago state, these vessels have undergone a change of form. Instead of the irregular mass spoken of above we find now several membranous filaments attached to the outer walls of the stomach and intestine, with the same enclosed circular bodies. What can be the use of these bodies I cannot guess, nor am I acquainted with anything at all similar to them in any other insect. The side view of these bodies will remind the reader of certain forms of Diatomaceæ, such as Navicula and Fragillaria, etc. The lower portion of the intestine is surrounded by a tangled mass of threads as fine as a spider's web. These are numerous distinct vessels which empty themselves a little above the anus. Fig. M represents two of these vessels magnified.

The ovaries (Fig. G) consist of two almond-shaped organs, which occupy nearly the whole of the abdominal cavity. The ova are unattached, and readily separate themselves in water. It is the possession of these ovaries that makes the insects such

fat delicacies for the hungry fish which feed on them. The eggs are deposited, it is probable, in small clusters; certainly not all at once, as some writers have asserted.

Mr. Griffiths (Anim. King., Insects ii. 321) tells us that "each Ephemera has seven or eight hundred eggs to lay, which is an affair of a moment, for she puts forth the two clusters at once" (!).

Swammerdam supposed that the eggs of the female were fertilized by the male at the moment of expulsion in the water, after the manner of fish; but there is doubt that the Ephemera does not differ from what obtains amongst other insects in this particular point.

The Ephemeride have all very short awl-shaped antennæ, hence the term Subulicornes proposed by Latreille, and very small hinder wings. In the genus Canis and in Cloë diptera the hind wings are entirely absent. The eyes are large; those of the male of Ephem. vulgata are much more prominent than the eyes of the female; the ocelli are three in number.

The term May-fly is very indefinite, standing for all sorts of different insects in different counties; here, in Shropshire, we generally restrict the word to the Ephemera vulgata. Anglers are often very positive that the green and grey drake are produced from the caddis worms, so abundant in every stream and pond, which are the larvae of various kinds of Phryganida.

As the term Cadow is used to denote the May-fly (Ephemera), it is probable that the name was given to it under the mistaken notion that it was produced from a case larva.

That the grey-drake is only the female green-drake metamorphosed, or rather after the last pellicle is cast, may be sometimes readily proved by dissection. The marble and white skin of the female grey-drake may be seen by carefully slitting open or peeling off the first integument of the greendrake.

The expressions green and grey drakes, as applied to the May-flies by anglers, owe their origin to the fact that the wings of the artificial fly are made from a mallard's feather, dyed olive for the green-drake, or immature condition of the insect; and from the same feather slightly stained with purple for the grey-drake, or perfect form of the female.

The figure on the left-hand blade of grass in Plate I. represents the female green-drake, which changes into the grey-drake, seen resting on the right-hand blade, leaving her cast-off pellicle upon the grass stem, as seen in the engraving. The flying insect is the perfect male.

THE THREAD-MOSSES.

BY M. G. CAMPBELL.

THE thread-mosses are an interesting and numerous tribe, containing upwards of fifty species, which have been parcelled out into eight distinct genera; but as space would fail us to describe them all, we shall, at the present time, only pass in review a portion of the Bryums, the chief genus.

They appear to derive their generic appellation from the Greek word Spû'ov, a moss, which would seem to say they were the first of this tribe of plants that attracted attention, and we can scarcely wonder at this when we behold their dense tufts crowned with innumerable beautifully-formed reddish or bright brown pendulous capsules, like eardrops of cornelian or coral awaiting some fairy hand to give them a golden setting; at all events the name is of very ancient origin, is found in the works of Dioscorides, the Sicilian physician, and has been applied by Dillenius to this genus and its affinities.

The mosses of this genus are perennial, have terminal fructification, of a pyriform, club-shaped, or oblong outline, smooth and inclined, pendulous, or sub-pendulous, with a tapering neck or apophysis, varying in length according to the species, and terminating a long fruit-stalk. They are found growing on rocks, on stone walls, on the ground, and sometimes, but rarely, on the trunks of trees. They have a double peristome, the outer consisting of sixteen equidistant, lanceolate, hygroscopic teeth, incurved or connivent when dry, transversely barred, the bars internally prominent, and externally the teeth are marked with a medial line. The inner

peristome is a membrane divided half way down into sixteen carinate processes, alternating with the outer teeth. Sometimes furnished with, and sometimes destitute of, intermediate cilia, which when present are filiform, and either solitary or two or three together.

The spores are rather small, smooth, globular, green, or reddish brown. The stem has innovations from the floral apex, which innovations resemble the parent stem, are either simple or branched, are tomentose with radicles, and by their issuing from the floral apex, instead of from the lower part of the stem, form, though not without an exception, one of the characteristic differences between the species apportioned to this genus and those assigned to the Mniums.

One of the most common examples of this family is the Bryum intermedium, or many-seasoned thread-moss, which

may be found in fruit from June to December, on walls and rocks, in sandy, clayey, or gravelly places; and it is remarkable for continuing to ripen its fruit in the same tuft at successive periods.

The

The illustration is somewhat larger than the natural specimen, and the single capsule considerably magnified, with its lid just starting and showing a portion of the teeth. stems when growing vary from two lines to half an inch in length, the barren branches being elongated, slender, and flagelliform, the rest shorter and fastigiate. The leaves are imbricated and erect, more or less spreading, and scarcely crisped when dry; the lower ones are reddish, all of them ovate acuminate, somewhat concave with a reflexed margin, which is sometimes denticulated, and an excurrent nerve. The inflorescence is synoicous, bearing both antheridia and archegonia on the same receptacle. The symmetrical capsule, is, as will be seen by the cut, narrowly pyriform, pendulous,

1

1, Bryum intermedium; 2, magnified capsule.

or sub-pendulous, with a long neck and rather a small mouth, surrounded by a reddish or purplish border, not becoming constricted below the mouth when dry, and having the lid, which is more or less apiculate, and the annulus sub-persistent, or remaining on longer than in the allied species.

Bryum argenteum, or the silvery thread-moss, is also an easily met with species. It fruits in October and November, and is at home almost anywhere, on the ground, by the waysides, on walls, or on roofs of houses, compacting its slender and fragile stems, of from a quarter of an inch to an inch long, into exquisite silvery white patches; the lower leaves scattered, broadly ovate and apiculate, the upper ones ovate, or ovatelanceolate, all of them very concave and imbricated, mostly apiculate, entire, not recurved in the margin, the nerve ceasing considerably beneath the point, the points colourless and more or less reflexed, and the areolæ lax.

The oval oblong capsule is attached to a fruit-stalk of about half an inch in length, which is suddenly bent at its junction with the capsule, and the latter is of a purplish or reddish colour when fully ripe, and becomes constricted below the mouth in the dry state, its convex lid obscurely pointed, and

its neck not tapering, but abruptly passing into the fruit-stalk, beautifully symmetrical and pendulous.

Bryum Zierii, or the Zierian thread-moss, also ripens its fruit in October and November. It grows in the crevices of rocks on the mountains of England, Scotland, Wales, and Ireland, planting them with its soft, pale, or silvery reddish, rather lax tufts, composed of stems from half an inch to an inch long, with julaceous, or slender glossy branches, whitish above and reddish below, somewhat resembling the last species in aspect, but larger, and always having a considerable tinge of red; the leaves are imbricated, roundish ovate in form, very concave, acuminate, entire, the margin not reflexed, but the apex, below which the nerve ceases, slightly recurved, the leaves of thin, membranous texture, the lower ones reddish, the upper longer and narrower, with the nerve extending nearer to the apex, and the reticulation loose. The capsule is more or less cernuous, large, of a reddish brown colour, clavatopyriform, and gibbous on the upper side, with a long, tapering incurved neck, rendering the mouth oblique. The small conical, acute lid covers an unequal peristome, the inner being longer than the outer, and having only rudimentary cilia, or none at all; the spores are rather large and brownish, and the mouth of the capsule, tenacious of its nurslings while within the enclosure, becomes enlarged after their exit. The fruitstalk is arcuate at the summit, and scarcely half an inch in length. Its more robust size, large and singular capsule, with the vinous hue of its foliage, sufficiently distinguish this interesting species from its nearest ally, B. argenteum. Both have a dioicous inflorescence.

Bryum demissum, or the club-fruited thread-moss, is not unlike B. Zierii in the form of its capsule, which is similarly oblique-mouthed, but its foliage, except in colour, resembles that of B. caespiticium. It is also altogether of a more compact and dwarfish habit than B. Zierii, its stems scarcely reaching a quarter of an inch in height, bound together by the small radiculose fibres which cover them, and the short innovations and branches which they put forth. The capsule, too, has a shorter neck, a more oblique mouth, an inner peristome proportionally longer, with irregular segments variously united, and short, mostly solitary cilia. Its leaves are reddish, but in other respects too closely resembling our common species B. caespiticium to require a separate description. It is very beautiful, and one of our rarer species, found only in the fissures of rocks in exposed situations; has been met with upon Craigalleach and other summits of the Breadalbane range, and fruits in August and September. Its inflorescence is

dioicous.