of these is a veritable colossus, the Hister maximus of Linnæus. A third group (Hololeptæ) are found only under the bark of trees; their heads are not retractable within the breast, and their bodies are excessively depressed, to fit them for living in narrow crevices, some kinds being literally as thin as a wafer. A fourth set of species (Trypanæus) form a perfect contrast to these, being cylindrical in shape. They drill holes into solid wood, and look like tiny animated gimlets when seen at work, their pointed heads being fixed in the wood whilst their smooth glossy bodies work rapidly round, so as to create little streams of sawdust from the holes. Several families of insects show similar diversities of adaptation amongst their species, but none, I think, to the same extent as the Histeridæ, considering the narrow limits of the group. The facts presented by such groups in the animal kingdom must be taken into account in any explanation of the way the almost infinite diversity of the forms of life has been brought about on this wonderful earth.
At length, on the 12th of February, I left Caripí, my Negro and Indian neighbours bidding me a warm "adeos." I had passed a delightful time, notwithstanding the many privations undergone in the way of food. The wet season had now set in; the low lands and islands would soon become flooded daily at high water, and the difficulty of obtaining fresh provisions would increase. I intended, therefore, to spend the next three months at Pará, in whose neighbourhood there was still much to be done in the intervals of fine weather, and then start off on another excursion into the interior.
