Eight leagues from Matagalpa we reached the small town of Tierrabona, where, as the name implies, the land is very good. Every house had an enclosure around it, planted with maize and beans: and though it was evident that the land was cropped year after year, it still seemed to bear well. We stopped at a small brook just outside the town, and ate some provisions we had brought from Matagalpa. Some speckled tiger-beetles ran about the dusty road, and on wet muddy places near the stream groups of butterflies collected to suck the moisture. Amongst them were some fine swallow-tails (Papilio), quivering their wings as they drank, and lovely blue hair-streaks (Theclae). The latter, when they alight, rub their wings together, moving their curious tail-like appendages up and down. Great dragon-flies hawked after flies; while on the surface of still pools "whirligigs" (Gyrinidae) wheeled about in mazy gyrations, just as they are seen to do at home. Savannahs, sparingly timbered, were next crossed; then we reached one of those level plains, with black soil and blocks of porous trachyte lying on the surface, which are swamps in the rainy season, and have for vegetation sedgy grasses and scattered jicara trees, cactuses and thorny acacias. Up to the time we passed, there had been no rain in these parts, and the plain was dry and bare, with great cracks in the black soil. The grass had not sprung up, not a breath of air was stirring, and the heated air quivered over the parched ground, forming in the distance an imperfect mirage. Directly overhead the noonday sun hung hot in the hazy sky. As we moodily toiled over the plain, my attention was arrested by a dust whirlwind that suddenly sprang up about fifty yards to our left. The few dry leaves on the ground began to whirl round and round, and to ascend. In a minute a spiral column was formed, reaching, perhaps, to the height of fifty feet, consisting of dust and dry dead leaves, all whirling round with the greatest rapidity. The column was only a few yards in diameter. It moved slowly along, nearly parallel with our course, but only lasting a few minutes. Before I could point it out to Velasquez, who had ridden on ahead, it had dissolved away. I had been very familiar with these air eddies in Australia, and had hoped to carry on some investigations concerning them, begun there, in Central America; but, though common on the plains of Mexico and of South America, this was the only one I witnessed in Central America.