have explained. It is this, that while many of the creatures I have named will bear the four hours' journey from Southend, some of them will not bear the twelve hours' transit from Plymouth, though equal care be apparently taken with the packing in both cases.* But when such packing is possible, the gain is enormous in everything. We often, at the Palace, get a couple of thousand of animals, or more, in packages weighing altogether not half a hundred-weight, while if the same animals needed to be conveyed in properly aërated masses of actual water, each creature would require a pound-weight of water, instead of only a fraction of a grain-weight to each. The money value of the moist plan is strikingly shown in the instance of shrimps, of which we use about a ton weight every year in the Crystal Palace Aquarium for feeding purposes, and we require them alive, because many animals refuse to eat them when dead (when, too, they rapidly decompose and become poisonous), and besides, we are obliged to

Mr. Herbert Ingall, for whose opinions on all matters I have the highest respect, gives the probably right explanation:

"In packing animals for travelling in a moistened substance, but to which the air has free access, we would certainly seem to be employing the most effective as well as the most convenient method of sustaining the life of the animals so treated, as the moisture keeps the tissues moist (to a certain extent) in the natural form, so as not to stop the circulation or other vital processes of the living things; the moisture facilitating the respiration by being in thin films, and therefore the more easily they absorb oxygen. In practice this manner of carriage is found to be successful in some cases for very long periods of time, and the question naturally arises,-If an animal so treated can live for four or twenty-four hours, why should the same method not be effective and successful for periods of forty or two hundred and forty hours? To answer this we can but suggest the reasons of the method being unsuccessful for the longer periods, and these suggestions be proved by experiment, as there are no doubt many causes acting together that result in the death of the animal. Let us consider what may be the causes. Least of all we may consider the (in the larger and more active animals at least) undesirable and cramped position that they must necessarily suffer from, and their inability to take food. But the most probable cause of death is this-that the quantity of air and oxygen supplied to the animal being often more than usual, the respiration and vital processes are more rapid, and the waste necessarily greater, as also therefore will be the excretions of the animal. When (and this period will of course vary according to circumstances) the excreta, not being removed, as they would be in the sea, become so great that the oxygen is all required to decompose the organic poisons (for such they are) the animal naturally dies of asphyxia, there being no oxygen available for the respiratory processes, or it may even die of organic poisoning. It is I think probable that this is the main cause of death after certain varying periods. Cold would of course retard it by lessening the rapidity of the vital processes. It perhaps might be proved experimentally by packing animals in the way described, and causing the removal of the effete matter in some way."

keep them in a living state till they are eaten from day to day. They are accordingly brought in baskets measuring eighteen inches long, twelve inches broad, and only two inches deep, and this small thickness enables the shrimps to be well aërated throughout on the journey. I devised this plan, as when they came in high baskets only those at the surface arrived alive. They cost us, in good condition, about a shilling a quart, but if it was necessary to bring them alive, in water, they would cost at least a guinea a quart! This system of exposing water to air in a state of exceedingly minute division may be seen in the Crystal Palace Aquarium in a kind of inverse application of the principle, the air as it descends being very finely pulverized in every tank, and all that the water can possibly absorb is taken up. It could not be so finely comminuted and diffused if it were made to ascend, and therefore the ascending plan is a very wasteful one.

To return to Limulus. They are brought from America in tubs or boxes containing a layer, two or three inches deep, of wet sand, which is kept moist by having water-sea or fresh waterthrown on it occasionally. Some travelled from New York to Liverpool in a deal-box kept moist by a bladder of water suspended inside it, and in this they again travelled from Liverpool to Hamburg. Some I by accident kept in some badly aërated sea-water in a vessel with steep sides, out of which the crabs could not climb for air. I removed them, apparently dead, and sent them to the City of Hamburg Museum to be put in spirits, but they revived on a cold damp stone-floor, where their gills became oxygenated, and were brought back to the aquarium, where they lived long.

At Professor Owen's request, I sent him some notes on the habits of Limulus in captivity, and he has printed my observations with his own in the Linnean Transactions' (vol. xxviii. pp. 471–472), thus:

"The ulterior pair of limbs are not for walking, but exclusively for burrowing. These limbs are terminated by four long stiff lobes of an oval or leaf shape, jointed at the base, on the leg, and capable of being opened and closed in a four-radiate manner. When it wishes to burrow, these two limbs are, sometimes alternately and sometimes simultaneously, thrust backwards below the carapace, quite beyond the hinder edge of the shell; and in the act of thrusting, the lobes or plates on each leg encounter the sand, the resistance or pressure of which causes them to open and fill with

the sand, a load of which at every thrusting operation is pushed away from under the crab, and deposited outside the carapace. The four plates then close, and are withdrawn closed, previously to being opened and charged with another load of sand; and at the deposit of every load the whole animal sinks deeper into its bed, till it is hidden all except the eyes. The great hiding shield of a carapace again prevents one from seeing whether this excavating work is aided by the fanning motion of the abdominal false feet, as is the case with the British lobster; but I think there is such fanning, as I have seen signs of sand being driven through the sand-orifices as if urged by a current of water.

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The tail-spine of Limulus is used in locomotion in the following manner :—The animal having climbed up a rock in the aquarium till it has got near to the top of a tank (which in Hamburg contained thirty inches of water in depth perpendicularly), and having assumed a vertical position, leaves go its hold on the rock, and allows itself to fall backwards; but its downfall is instantly checked, and the creature propelled upwards by a downward flap of all the strong overlapping false feet; and when the impetus given by them has ceased, the animal sinks down, but is prevented from falling prone on the floor of the tank by alighting on the tip of the perpendicularly hanging-down spine. The moment that is done, and before the creature has lost its balance on the spine, the false feet make another flap, and give another impulse upwards and forwards; and so it progresses by a combination of swimming and hopping, or by a succession of slow hops on one leg, as it were; and all this time the position of the carapace is slanting, the top of the carapace inclining downwards at an angle of about 45°, the second segment of the body being at another inclination, and the tail-spine hanging freely vertically, as before mentioned; and by being brought down by its joint at various deviations from the upright one, the spine changes the direction of the march, while the false (swimming) feet effect the actual propulsion. The Limulus was fond of thus going about at night (generally remaining in the sand all day). Another use was made of the tail-spine, as a lever by means of which it righted itself when it fell off a rock on its back. The spine is then bent; i. e. its point is planted in the sand, so that it makes an acute angle with the carapace, which is then so far raised that some of the feet are enabled to grasp a projecting surface, either longitudinal or vertical, or at some combination of the two; and the crab then turns over."

Limulus has often caused me to be undeservedly blamed, because they so constantly hid themselves in sand by day in the perfectly aërated water of the Hamburg and Crystal Palace aquaria, while in the imperfectly aërated water of the aquaria of Hanover and Berlin they climbed about the rocks all day, at their surface, and of

course in sight of visitors, because they were seeking for air. So many unthinking people ascribed my inefficient exhibition of these animals to my want of skill, forgetting how many other animals died from the badly aërated water in the places I have named.

Sesarma was brought alive from the Navigator Islands to Hamburg in a slow sailing-ship. It is, as I have already named, a relative of our British crab Gonoplax, which never walks out of water. At first the captain of the vessel put some of his captives in a vessel of water out of which they could not crawl, and the water being but imperfectly aërated, the crabs soon died. So he arranged a box with moist earth and sand, and in this the remaining specimens burrowed, and came out occasionally, and did well. I noticed, without being told by persons or books, that the surface of the pterygostamian regions of the living Sesarma I had in Germany was reticulated, or granulated, by being divided into numerous small regular squares, and that these retained much water by mechanical entanglement. On my telling my friend Dr. F. Hilgendorf, then of Hamburg and now of Yokohama, that I suspected that this arrangement was to enable the crabs to carry about with them their own aquaria of perfectly aërated (because shallow) water, he said it was so, and that some sharp German biologist, whose name I forget, had made the discovery before I did.

Cenobita Diogenes is a powerful West Indian land hermit-crab, living in a univalve shell like our British hermits, but spending much of its time out of water, entering it, I believe, only for depositing its eggs. Yet it is, of course, a gill-breathing animal, needing water to moisten its gills, and so enabling its blood to be purified. How very small the quantity of water it needs may, however, be judged when I say that the first living example I saw was given me by a Swedish carpenter, who brought it from Stockholm in his jacketpocket, where he had kept it for some weeks previously as a pet. The next I saw was a lot of twenty brought from the mouth of the river Gibarra, in Cuba, to Hamburg in a sailing-vessel. They were found walking about in the burning sun on sand which was all the hotter because black. I went on board to fetch them, and found them in an old cigar-box, which was wrapped in a sailor's "Guernsey" to keep it warm in the hot cookingplace or caboose. Some of the sailors said the crabs fed on tobacco, and others that they ate potato-peel, so both of these substances were placed in the box, on opening which the stench

proceeding from it was awful. But the crabs were alive and well. On opening the window of the cab on my way to the Zoological Gardens, I let in some air, and, the day being very cold, the crabs soon became torpid, and, losing hold of their shells, gradually fell out of them as if dead, and I was in great trouble. I, however, put them in a tray before the fire of the aquarium steam engine, and they soon revived, and, walking about, repossessed themselves of their shells. I afterwards kept them upon damp hot sand, at a temperature of 95° F., and fed them on meat for several months. They would never stop long in the aquarium tanks, but crept out and walked on the floor among visitors.*

Gegarcinus was kept several times in the Regent's Park Zoological Gardens long before there was an aquarium there. The most important thing yet done in this way of comparatively dry transmission was the sending of trout-eggs from Britain to Australia, and there hatching them in such a successful manner that large trout are now found at the antipodes. The eggs were packed in perforated chip-boxes lined with moist moss, and thus the ova had both air and water (a little, but enough, of both) circulating in the interspaces left by the round eggs. In addition, they were kept cold by ice, and the low temperature thus retarded the hatching on the voyage by diminishing the rapidity of respiration, and thereby much lessened the demand for oxygen.

We all know how medicinal leeches-which are, of course, gillbreathing animals-are sent from country to country packed in moist earth, and that enclosed in bags, with no great per-centage of death. Also how eels, periwinkles, mussels, cockles and oysters are transported nearly dry, yet alive and well. Oysters and clams even come to Britain alive from America. Sea-anemones and many other aquatic creatures, including small carp and tench, are frequently sent by post, in moist packing, alive. If these animals had to be transported in water, the weight and trouble would be so great that a trade in them could never be remunerative. What I want, therefore, is to more generally and economically apply to Natural History what has been done for commerce.

At about the same period there were some Cenobita in the London Zoological Gardens, and I wrote there to know what food I should give mine, and the perfectly serious reply was, " Oatmeal boiled into hard dumplings!"

SECOND SERIES-VOL. IX.

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