[P] The air-pipes are two vessels, one on each side, extending the whole length of the body, provided with branches and ramifications. They serve for the reception and distribution of the air. [Illustration] CHAPTER XXIV. A LABORIOUS TASK.--WILD LIME-TREES.--PIGEONS.--THE WEST INDIAN CHERRY.--THE EARWIG.--SNAKES AND SERPENTS.--FIRST GLANCE AT THE TERRE-CHAUDE. "How is your arm now, l'Encuerado?" I asked, finding the Indian up when I awoke. "Pretty well, Tatita; but I find I mustn't move it much. If I do, it feels as if the blackguard water-dog was still holding me." I again dressed the wound, the Indian continuing to hurl fresh abuse at the otter. I made him keep quiet, and prepared the coffee. Sumichrast and Lucien then rose, and we decided to start--the rainy season, which was approaching, rendering haste necessary. L'Encuerado, in spite of our remonstrances, insisted on shouldering the load; but, on raising the burden, he found he was unable, so I shouldered the load. At last, after no end of exertion on my part and Sumichrast's--for we alternately bore it--three leagues were traversed. We then halted at the foot of a hill, among ebony, mahogany, and oak trees. L'Encuerado took charge of the camp, while I, with my friend and Lucien, climbed a neighboring hill. The trees which crowned its summit were limes--_Tilia sylvestris_--here the type of what bear the same name, and which are so plentiful in Europe, where they have been so changed by cultivation that they scarcely appear to belong to the same species as their brethren in the virgin forests. The wood of the lime is valued by the Indians for making various odds and ends, which are sold by thousands in Mexico. In Europe, the bark of this tree is used for well-ropes, and the charcoal made from its wood is preferred to any other for the manufacture of gunpowder. Few trees are more useful, and its beautiful green foliage makes it highly ornamental in a garden. Our attention was attracted to a familiar noise--the cooing of doves. I moved gently under the trees, and soon put to flight several fine specimens, of a dark, ashy-blue color, with a black band across the tail-feathers, which were of a pearl-gray. I killed a couple of them; and Sumichrast, who was better placed, knocked down three others. They were quite sufficient for our dinners. They were the first of this family that we had killed, and Lucien in vain tried to make out what he called their relationship. "They are neither passerines," said he, "nor palmipedes. Climbers, too, have differently-made feet." "Your doubts are very natural," interposed my friend; "even ornithologists are very undecided on this point. Nevertheless they class pigeons among the gallinaceae, looking upon them as a link between this order and the passerines." "Why don't they make an order for them by themselves?"