covered that he actually did not know himself where it was, but was seeking for another man to show him. We at last arrived at the house of this man. He was absent. A boy showed us a small piece of the limestone. It was concretionary, and I learnt from him that it occurred in veins. I was vexed about the time we had lost, and the extra work we had given the poor mules; my only consolation was that as we rode back I picked a fine new longicorn beetle off the leaves of an overhanging tree.

When we came to settle up with our host he proposed to charge us twenty-five cents, just one shilling, or fourpence each. They had given us a good dinner and put themselves to much inconvenience to provide me with a bedstead, and this was their modest charge. Nor did they make it with any expectation that we would give more. It is the universal custom amongst the Mestizo peasantry to entertain travellers; to give them the best. they have and to charge for the bare value of the provisions, and nothing for the lodging. We could so depend upon the hospitality of the lower classes that every day we travelled on without any settled place to pass the night, convinced that we should be received with welcome at any hut that we might arrive at when our mules got tired or night came on. The only place in the whole journey where we had been received with hesitation was at the Indian house a day's journey beyond Olama. There the people were pure Indians, and other circumstances made me conclude that the Indians were not so hospitable as the Mestizos.

We finally started about nine o'clock and rode over dry savannahs, where, although there was little grass, I

was told that cattle did well browsing on the small brushwood with which the hills were covered. All the forenoon we travelled over stony ranges and dry plains and savannahs. At noon we reached the dry bed of a river and crossed it several times, but could find no water to quench our thirst, whilst the sun shone down on us with pitiless heat. About one o'clock we came to some pools where the bed of the river was bare rock with rounded hollows containing water, warm but clean, as the cattle could not walk over the smooth slopes to get at it. Here we halted for an hour and had some tiste and maize cakes, and cut some Guinea grass that grew amongst the rocks for our mules. Over the heated rocks scampered brown lizards, chasing each other and revelling in the sunshine. Butterflies on lazy wings came and settled on damp spots, and the cicada kept up his shrill continuous monotone, but not so loudly as he would later on when it got cooler. The cicada is supposed by some to pipe only during midday, but both in Central America and Brazil I found them loudest towards sunset, keeping up their shrill music until it was taken up by night-vocal crickets and locusts.

We were returning parallel to our course in going to Segovia, but several leagues to the westward, and this made a wonderful difference in the climate. There we were wading through muddy swamps and drenched with continual rains. Here the plains were parched with heat, vegetation was dried up, and there was scarcely any water in the river beds. The north-east trade-wind, before it reaches thus far, gives up its moisture to the forests of the Atlantic slope, and now

passed over without even a cloud to relieve the deep blue of the sky or temper the rays of the sun.

The vegetation on the plains was almost entirely composed of thorny plants and shrubs; acacias, cacti, and bromelia were the most abundant. Animal life was scarce; there were a few flycatchers amongst the birds, and armadilloes were the only mammals. Horseflies (Tabanus) were too numerous, and drops of blood trickled down our mules' faces where they had feasted. In some parts large, banded black and yellow wasps (Monedula surinamensis, Fabr.) came flying round us and had a threatening look as they hovered before our faces, but they were old acquaintances of mine in Brazil, and I knew that they were only searching about for the horse-flies with which they store their nests, just as other wasps do with spiders, first benumbing them with their sting. I noted here another instance of the instinctive dread that insects have of their natural enemies. The horse-flies were so bloodthirsty that we could kill them with the greatest ease with our hands on the mules' necks, or if we drove them away they would return immediately. As soon, however, as a wasp came hawking round, the flies lost their sluggish apathy and disappeared amongst the bushes, and I do not think that excepting when gorged' with blood they would easily fall a prey to their pursuers.

We were joined on the road by a storekeeper on his way to Teustepe. He was armed with pistols, which it is the fashion to carry in Nicaragua, though many travellers have nothing more formidable in their holsters than a spirit flask and some biscuits. He talked as usual of threatened revolutionary risings, but these form

the staple conversation throughout Central America amongst the middle classes, and until they really do break out it is best not to believe in them. He told us also that the drought had been very great around Teustepe, and that the crops were destroyed by it.

About three we reached the town, and after buying some provisions to take with us, pushed on again. Below Teustepe we crossed the river Malacatoyo which empties into the Lake of Nicaragua, and beyond it the road passed over a wild alluvial flat with high trees, amongst which we saw a troop of white-faced monkeys.

On the leaves of the bushes there were many curious species of Buprestidæ, and I struck these and other beetles off with my net as I rode along. After one such capture I observed what appeared to be one of the black stinging ants on the net. It was a small spider that closely resembled an ant, and so perfect was the imitation that it was not until I killed it that I determined that it was a spider and that I had needlessly feared its sting. What added greatly to the resemblance was that, unlike other spiders, it held up its two forelegs like antennæ, and moved them about just like an ant. Other species of spiders closely resemble stinging ants; in all of them the body is drawn out long like an ant, and in some the maxillary palpi are lengthened and thickened so as to resemble the head of one.

Ant-like spiders have been noticed throughout tropical America and also in Africa.* The use that the deceptive resemblance is to them has been explained to be the facility it affords them for approaching ants on * See "Nature," vol. iii. p. 508.

which they prey. I am convinced that this explanation is incorrect so far as the Central American species are concerned. Ants, and especially the stinging species, are, so far as my experience goes, not preyed upon by any other insects. No disguise need be adopted to approach them, as they are so bold that they are more likely to attack a spider than a spider them. Neither have they wings to escape by flying, and generally go in large bodies easily found and approached. The real use is, I doubt not, the protection the disguise affords against small insectivorous birds. I have found the crops of some humming-birds full of small soft-bodied spiders, and many other birds feed on them. Stinging ants, like bees and wasps, are closely resembled by a host of other insects; indeed, whenever I found any insect provided with special means of defence I looked for imitative forms, and was never disappointed in finding them.

Stinging ants are not only closely copied in form and movements by spiders but by species of Hemiptera and Coleoptera, and the resemblance is often wonderfully close.* All over the world wasps are imitated in form and movements by other insects, and in the tropics. these mimetic forms are endless. In many cases the insect imitating is so widely removed, in the normal form of the order to which it belongs, from that of the insect imitated, that it is difficult to imagine how the first steps in the process of imitation took place. Looking however at the immense variety of insect life in the

* Amongst the longicorn beetles of Chontales, Mallocera spinicollis, Neoclytus Esopus, and Diphyrama singularis, Bates, all closely resemble stinging ants when moving about on fallen logs.