representations of photographs of the refrangible portion of the solar spectrum, and of that of the metal magnesium. Though these have not been reduced to the same scale, the impression is a correct one, that that of magnesium extends much beyond the solar, and especially will it be noticed, is there a remarkably strong band in the magnesium spectrum just beyond the limits of the solar. Yet no metal has been proved to be present in the sun with more certainty than magnesium. Professor Miller regards this difference as an indication of the solar temperature. The magnesium spectrum was obtained by the electric spark. If, in place of this intensely high temperature, the oxyhydrogen flame of only 15 000 F. be substituted, the magnesium spectrum is shortened, and does not extend beyond that of the sun. From this Professor Miller infers that "the temperature of the sun may be approximately estimated to be not higher than that of the oxyhydrogen flame. It certainly appears to be far below that of the electric spark." This seems to be scarcely in accordance with the known law of the decrease of radiant heat. This decreasing, inversely as the square of the distance, gives an intense amount of heat to the solar surface. Waterston, in a communication to the Royal Astronomical Society in February, 1860, states that his experiments, founded upon the supposition that the difference between the temperature in the sun and the temperature in the shade, is a function of the sun's absolute temperature, give above "ten million degrees, probably twelve million, Fahrenheit," to the solar surface.

Is it not possible that vapours may exist in the solar atmosphere which, as Professor Miller shows to be the case with sulphuretted hydrogen, are but imperfectly diactinic, and so arrest these extreme rays of energy? Not that sulphuretted hydrogen, or any compound body, can be supposed to exist upon the solar surface. The elements there must stand too much aloof, by the mutual hate of the fierce heat, to unite themselves in alliances with each other. It may be, however, that conditions unknown to us alter or modify the terrestrial law of decrease of heat.

It seemed, however, an object of great interest to know if similar photographic spectra could be obtained of the stars. The writer and Dr. Miller have already been successful in photographing the more refrangible portion of the spectra of Sirius and Capella. The further prosecution of this investigation is necessarily deferred for the present.

"One star differeth from another star in glory, in wisdom hast Thou made them all."

THE FEET OF HYMENOPTERA.

BY L. LANE CLARKE.

(With a Tinted Plate.)

IT will be difficult to bring the feet of Hymenoptera within the compass of one paper, inasmuch as it is impossible, I think, to look at the claws and legs of these insects without consideration of the purposes for which they are modified and adapted, in the various species of this very numerous tribe.

We have now before us, besides our microscope, the mounted legs of bees, wasps, saw-flies, ichneumons, and ants; the first thing we notice is that the entire leg is composed of five joints, as in the Diptera, but with the trochanter divided into two parts, slightly articulated. The tarsal joints are invariably five, but differ considerably in length and in the form and number of their appendages. In fact, an intelligent observer will collect most interesting materials for his microscope by examining the legs of Hymenoptera, of which only a few are now figured to give an idea of their variety and strange forms.

Let not even the tiniest gall-fly or ichneumon escape notice, and if you are so fortunate as to possess a "binocular," the legs may be mounted dry on a disk of light green paper, when every spine and hair will be thrown up round and distinct under the deflected light.

For transmitted light, and the polarizing apparatus, these feet and legs must of course be mounted in balsam, and the legs. of bees will require long soaking in potash, or a week at least of hydrochloric acid, to bleach them.

The hind leg of a bee is so well known with its basket and brush, that we need not do more than advise the mounting of the hollowed tibia, and the dilated first joint of the tarsi, edged with strong curved bristles, on the outer side of which is the collecting brush, having ten rows of hairs, and from sixteen to twenty-four hairs in each row (Fig. 1). But, having mounted the hive bee's leg, there will be a most interesting variety in those of the small humble bee, carder bee, and leaf-cutter bees (Megachile). The spines upon the tarsal joints, and the different arrangement of hairs in the brush, are worthy of attention. The pulvillus and claws of the hive bee should be taken from young ones just hatched, being more transparent then. The membranous sucker is folded up when at rest, and inflated into a cup-like disk, edged with adhesive hairs, when the foot is in action (Fig. 1).

Nor should the anterior legs be neglected, for they have in most bees a very curious notch and spur, unmentioned in popular bee-books. The hive bee has a deep notch on its fore tarsi, edged with short hairs, and above, on the extremity of the tibia, a moveable spur, strong and sharp, which forms a handy pair of pincers, and which I have seen used very effectively under certain circumstances (Fig. 2). When the honeybees drag a dead intruder from the hive, they use their foot, jaws, or mandibles only; but when they fight a wasp, or expel a refractory drone, they use their fore-leg to clasp and hitch into that notch a leg of their opponent, neither drone nor wasp having the same useful appendage to make the fight an equal one.

In the fore-leg of the Bombida-humble-bees and carderbees-the notch and spine are still more developed (Fig. 3). The spur has a strong sharp point, and a horny blade like a pocket-knife, the very thing these little workmen needed for hackling their moss, and building their cells.

The pretty spotted bee (Melecta punctata) which hovers over the bright furze blossoms from March to June, has a winged spine on its fore tibia, and the tarsi are beautifully pilose, as if silvered with delicate metallic hairs (Fig. 4); the claws are deeply toothed, the pulvillus very distinct, and mounted dry on a disk of blue paper it is a beautiful object for the binocular.

The leg of Mesotrichia (Fig. 5) is given merely as an example of variation, for which there is doubtless reason good in the habits of the bee. It is a South American insect, and builds in cavities near the summit of trees. The strange dilatation of the basal joint of its tarsi and curled tufts of hair, as well as the strong spine on the third joint, and triangular tufts of hair, are very remarkable.

The curious feet of Dryinus cursor (Fig. 6) are figured to show the position of claws and pulvillus. The fore tarsi have only a single claw, serrated and reflected backwards, whilst the pulvillus is inflated and porrected forwards. The hind tarsi have two small claws, much dilated at the base, and a very large pulvillus. The entire insect should be mounted in balsam. This small ichneumon may be taken from June to August; the females are apterous, the males look like winged ants running over the herbage.

The small ichneumon, Smiera, has most singularly curved tibia and tarsi (Fig. 7). This fly may be taken on the banks of ponds and quiet rivers, where it hovers watching for the larvæ of Strationidæ, in which it deposits its eggs. The Stratiomys is a black and yellow fly, which passes the first part of its existence as an aquatic larva, with a beautiful apparatus

for breathing-a coronet of hairs terminating its body, which is spread out like a star on the surface of the water, and enables the insect to take in a full supply of air.

But it is in the family of the Fossorial Hymenoptera that the strangest form is found. The Crabro cribrarius has a dilatation of the fore tibiæ and tarsi into a concavo-convex plate, apparently soldered on these joints; it is pierced with small dots, each covered with a transparent membrane, which is capable of inflation and adhesion, probably for the same purpose as the sucker on the foot of the male Dyticus (Fig. 8). This insect haunts the umbelliferæ in July and August.

The Ammophila campestris, another of these burrowing wasps, besides some strong hooked claws, possesses a remarkable toothed spur at the lower end of the fore tibia, and the upper tarsal joint is edged with stout bristles (Fig. 9). Now I doubt not that these act 'as rakes, and also as grapples, for the work of this fossorial insect is by no means easy. I well remember lying under an apple tree at Woodlands one hot summer's day in July, my eye was attracted by a wonderful orange-coloured creature toiling across the gravel walk, dragging a fat grass-green caterpillar. I was a child then, and knew no scientific names; the romance of natural history was my delight, and so I watched the progress of this poor caterpillar in its enemy's jaws. The larva writhed, and twisted, and clung to every pebble on its way, and the fierce Ammophila tugged, and pulled, and got it along somehow, over the gravel, and on to the flower-bed beside me. Then it dropped the caterpillar, which only faintly tried to crawl away, and had not time to move an inch before back came the fly, which had removed a pellet of earth close by, and discovered a deep-looking hole. This was, doubtless, her nest, and seizing the caterpillar she began to back into the aperture; the fat grub was hard to manage, but the legs and feet of the Sphex were set firmly against the sides of the tunnel, these spurs erect, doubtless, and forming a strong finger or toe behind the tarsal joints, which gave her good help in the descent, for, more speedily than I could have believed, they both vanished from my sight. About two minutes elapsed, and the Ammophila re-appeared, quickly replaced its pellet, and concealed the aperture so effectually that I could not find it when, after watching the flight of the insect for a moment, I turned to examine the nest.

This Ammophila was not so obliging as the one observed by Ray in 1667, who, after building in and treading down the earth within its burrow, brought two fir leaves and marked. the spot, which enabled him to investigate the contents of her excavation,

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