Cerceris merely relinquishes her captive for an instant at the entrance, in order to turn round and crawl backwards--thus more conveniently pulling him after her. Why then should the Sphex persist in paying this domiciliary visit before introducing her victim? Perhaps through apprehension lest one of the Tachytes, who make use of the same kind of cells for their offspring, and are accustomed to provision them in like manner, should have taken advantage of the lawful owner's absence, to deposit an egg in the cell ready scooped out. But however this may be, the manœuvres of the Sphex are invariably the same. M. Fabre's experiments on this head are very curious. He took advantage of her momentary absence to remove the grasshopper, and place it at a few inches distance. The proprietor returned, uttering her usual cry, looked anxiously about, and finally, perceiving her prey, dragged it back to her door, and placed it again in precisely its former position; then leaving it, descended as before into her nest. The same process was repeated by M. Fabre thirty or forty times, in the hope that the Sphex, taught by experience, would cease to lose sight for a moment of her captive and convey it at once into the earth. But the perseverance of the insect triumphed over that of the philosopher; or rather, her acts not being dictated by reason, she knew not how to leave the path marked out for her by instinct.

In the case also of a Sphex albisecta, an inflexible adherence to settled laws in this respect was strikingly manifest, presenting a still more curious instance of the rigidity of instinct and its inapplicability to unusual conditions. Having, in the course of one of his experiments, removed her victim from the sight of a Sphex albisecta, M. Fabre observed the insect, after seeking vainly in all directions, descend for a few instants into her cell, and then emerging, proceed to cover up the entrance, as if her task were now satisfactorily accomplished; a striking exemplification of the manner in which acts of instinct depend one upon another, and admit of no variation, notwithstanding that their object may be entirely defeated by the alteration of surrounding circumstances. In the normal state of things, observes M. Fabre, the Sphex pursues her prey, lays an egg and closes her nest; an accident deprives her of her booty; no matter-that part of her duty is over, she therefore performs the remainder, and shuts up the unlucky egg quite unprovided for. Think of the melancholy fate entailed by maternal stupidity upon the helpless little new-born larva-fancy it emerging from the shell, in the full expectation of a satisfactory meal, and the miserable disappointment awaiting it, ending in despair and a lingering death. Many larvæ must so perish; for the case abovementioned is by no means exceptional. M. Fabre repeated the experiment several times, meeting almost invariably with the same results; and on opening the nests he frequently found cells either supplied inadequately with provisions, or containing none at all.

The rest of this paper is chiefly anatomical, and devoted to an

account of the metamorphoses undergone by those larvæ which are fortunate enough on leaving the shell to find their larders well supplied; but we must pass on to give a short summary of M. Fabre's paper on the habits and metamorphoses of Sitaris humeralis.

This interesting beetle is parasitic on Anthophora, in the galleries of which it lays its eggs. These are hatched at the end of September or beginning of October; and M. Fabre not unnaturally expected that the young larvæ, which are active little creatures with six serviceable legs, would at once eat their way into the cells of the Anthophora. No such thing: till the month of April following they remain without leaving their birthplace, and consequently without food; nor do they in this long time change either in form or size. M. Fabre ascertained this, not only by examining the burrows of the Anthophoras, but also by direct observation of some young larvæ kept in captivity. In April, however, his specimens at last threw off their long lethargy, and hurried anxiously about their prisons. Naturally inferring that they were in search of food, M. Fabre supposed that this would consist either of the larva or pupa of the Anthophora, or of the honey with which it stores its cell. All three were tried without success. The two first were neglected, and when placed on the latter they hurried away, or perished in the attempt, being evidently unable to deal with this sticky substance. M. Fabre was in despair: "Jamais experience," he says, "n'a éprouvé parcille déconfiture. Larves, nymphes, cellules, miel, je vous ai tout offert; que voulez-vous donc, bestioles maudites ?"

The first ray of light came to him from our countryman, Newport, who ascertained that a small parasite found by Leon Dufour on one of the wild bees, and named by him Triungulinus, was, in fact, the larva of the Meloe. The larvæ of Sitaris much resembled Dufour's Triungulinus, and acting on this hint, M. Fabre examined many specimens of Anthophora, and found on them the larvæ of his Sitaris. The males of Anthophora emerge from the pupa before the females, and as they come out of their galleries, the little larvæ fasten upon them. Not, however, for long: their instinct teaches them that they are not yet in the straight path of development; and watching their opportunity they pass from the male to the female Bee. Guided by these indications, M. Fabre examined several cells of Anthophora: in some, the egg floated by itself on the surface of the honey; in others, on the egg of the Anthophora, as on a raft, sat the still more minute larva of the Sitaris. The mystery was solved. By a process of reasoning too long for us to insert, M. Fabre convinced himself that at the moment when the egg is laid, the Sitaris larva springs upon it. Even while the poor mother is carefully fastening up her cell, her mortal enemy is beginning to devour her offspring. For the egg of the Anthophora serves not only as a raft, but as a repast. The honey, which is enough for either, would be too little for both; and the Sitaris, therefore, in its first meal, relieves itself from its only rival. After eight days the egg is

consumed, and on the empty shell the Sitaris undergoes its first transformation. The life of almost all insects is divided into four stages; the Egg, Larva, Pupa, and Imago: the larva, indeed, may moult several times, but the conditions of life being unaltered, the form is generally the same, and the change is only in size. Very different is the case with our Sitaris: the honey which was before fatal is now necessary; the activity which before was necessary, is now useless; consequently, with the change of skin the active, slim larva changes into a white, fleshy grub, so organised as to float on the surface of the honey, with the mouth below, and the spiracles above the surface; "grace a l'embonpoint du ventre, la larve est à l'abri de l'asphyxie." In this state it remains till the honey is consumed; then the animal contracts, and detaches itself from its skin, within which the other transformations take place. In the next stage, which M. Fabre calls the Pseudochrysalis, the larva has a solid corneous envelope, and an oval shape, and in its colour, consistence, and immobility reminds one of a Dipterous Pupa. The time passed in that condition varies much. When it has elapsed, the animal moults again, and once more resembles the second stage (?). After this it becomes a pupa without any remarkable peculiarities; and finally, after these wonderful changes and adventures, in the month of August the perfect Sitaris makes its appearance.

We wish that we could have done M. Fabre's paper more justice; that we could have given some specimens of his peculiar raciness of style, his wonderful power of description. But already we have been tempted beyond our limits. We can do no more than mention his observations on Meloe, and his excellent paper on the Myriapodes. All lovers of nature, however, should read what he has written, and we think we can promise them that they will not be disappointed. For ourselves, we offer our cordial thanks to M. Fabre for the pleasure which his writings have given us.

XIV.-A HISTORY OF BRITISH SESSILE-EYED CRUSTACEA. By C. Spence Bate, Esq., F.R.S., F.L.S., and J. O. Westwood, Esq., M.A., F.L.S., Hope Professor of Zoology at Oxford. (J. Van Voorst.) RECHERCHES SUR LA FAUNE LITTORALE DE BELGIQUE; CRUSTACÉS. Par P. J. Van Beneden, Professor a l'Université Catholique de Louvain.

THE work which we have placed at the head of the present article, and of which three numbers only have as yet appeared, will be a very valuable addition to our knowledge of the British Crustacea. The classification proposed by Messrs. Spence Bate and Westwood is as follows:

lorchestes, Nicæa.

Tribe.

Family.

Subfamily.

Saltatoria-Orchestiida.

Stegocephalides
Lysianassides

Natatoria-Gammaridæ

Ampeliscides
Phoxides

Gammarides

Podocerides

Corophiida

Domicola

Corophiides

Chelurida

Hyperiida

Phronimida

Dulichiide

Caprellidae

Cyamida

Montagua, Danaia.
Lysianassa, Callisoma,
Anonyx.
Ampelisca.

Phoxus, Sulcator, Kroi-
yira, Westwoodia,Gray-
ia, Monoculodes, Am-
philochus, Darwinia,
Urothoë, Lilgeborgia,
Phædra, Isæa, Iphime-
dia, Otus, Acanthono-
tus.
Gammarus, Dexamine,
Atylus, Pherusa, Cal-
liope, Eusirus, Leuco-
thöe, Aora, Stimpsonia,
Protomedia, Bathypo-
reia, Niphargus, Cran-
gonyx,
Gammarella,
Melita, Mæra, Mega-
mæra, Eurystheus, A-
matiha, &c.

Podocerus, Cyrtophium,
Amphitöe, Sunamphi-
töe, Cerapus, Siphono-
cætus, &c.

Corophium, Dryope, Cratippus.

Chelura.

Hyperia, Lestrigonus.
Phronima.

Dulichia.

Proto? Protella, Caprella.
Cyamus.

The three principal divisions of the body they call Cephalon, Percion,
and Pleon; for the parts of the mouth they propose the new name
"Siagonopods," a term, however, which seems to us unnecessary; the
appendages of the Pereion are with them pereiopods, and those of
the Pleon, pleopods, in addition to which they give to the three
posterior pairs the designation of 1st, 2nd, and 3rd uropods. The
internal anatomy of the Amphipoda does not come within the scope
of their work, but in addition to an excellent outline sketch of each
species, they give magnified representations of the more charac-
teristic organs. On the whole the work will be a most valuable
contribution to our knowledge of the British Fauna; but we must
defer any farther consideration of it till it is completed.

The volume for which we are indebted to the learned Professor
of Louvain is rather a series of monographs than a complete work
on the Crustacea of Belgium. The first chapters are devoted to the

Myside. The development of the embryo in this abnormal family had already been shortly described, but Professor Van Beneden has here worked it out in detail, and has pointed out several interesting facts in addition to those already known.

66

The Mysida have no true branchia; but in connection with the heart there are, on each side, five small lateral blood-vessels, and according to Professor Van Beneden, "Ces canaux correspondent exactement aux vaisseaux branchiaux des crustacés plus élevés, et "c'est sur leur trajet que se développent les lamelles branchiales des "décapodes en général. Il existe ainsi une petite circulation; le sang sort du cœur et, après avoir, parcouru la place qu'occupent "les branchies dans les autres décapodes et surtout après avoir reçu "un confluent veineux des appendices céphaliques, retourne rapide"ment au même cœur pour en être chassé de nouveau." Professor Van Beneden considers that Mysis differs from the other Crustacea in the curvature of the body of the embryo. "Il est inutile," he says, "de faire remarquer que les Mysis s'eloignent des crustacés, tant par "les premiers rudiments de l'apparition blastodermique que par la "manière dont le corps se replie sur lui même. En général l'abdomen "et la queue se plient sous le thorax et se croisent avec les appendices cephalothoraciques. Dans les Mysis, le corps se replie en sens "inverse vers le dos, et tous les appendices, depuis ceux de la tête 'jusqu'a ceux de la queue, au lieu de se croiser, sont couchés dans le "mème sens." Not only, however, is this the case, as he admits in the allied genera Idothea and Ligia, but we find the same thing also in Oniscus and Asellus (Rathke Abhandlungen zur bildungs- und entwickelungs-Geschichte des menschen und der Thiere. Leipsig, 1832-1833). And it is also well shown in Zaddach's beautiful memoir on the embryology of Phryganea (Untersuchungen über die Entwickelung und den Bau der Gliederthiere. Berlin, 1854). the Diptera and Coleoptera, namely in Donacia crassipes among beetles, in Chironomus,* Simulia (see Kolliker's "Observationes de primâ insectorum genesi"), and Melophagus (Die Fortpflanzung und Entwickelung der Pupiparen, Leuckart), among flies, the same phenomenon holds good; so that far from regarding it as exceptional and peculiar to Mysis, we are rather disposed to look upon it as the normal disposition of the embryo among the Articulata.

66

The condition and embryonic development of the organs of sensation in Mysis are especially interesting. With reference to the ocular peduncles, indeed, Professor Van Beneden says, p. 62, "Ce pédicule "(le pedicule oculaire) n' apparait aucunement comme les autres appen"dices, et semble avoir une autre valeur morphologique;" an assertion, however, which appears scarcely reconcileable with his, almost imme

With reference to Chironomus, Kolliker expressly says:- Quando primum "corporis articulatio expressa cerni potest, primus ad octavum usque articulum in "parte abdominali, nonus ad tertium decimum in ori dorso siti sunt"-a position which is well shown in the plate.