Page:The naturalist on the River Amazons 1863 v1.djvu/234

 body in one species, and in a totally different part in nearly allied ones. I tried in vain to discover the use of these curious brush-like decorations. On the trunk of a living leguminous tree, Petzell found a number of a very rare and handsome species, the Platysternus hebræus, which is of a broad shape, coloured ochreous, but spotted and striped with black, so as to resemble a domino. On the felled trunks of trees, swarms of gilded-green Longicornes occurred, of small size (Chrysoprasis), which looked like miniature musk-beetles, and, indeed, are closely allied to those well-known European insects.

I was interested in the many small kinds of lignivorous or wood-eating insects found at Caripí, a few observations on which may be given in conclusion. It is curious to observe how some small groups of insects exhibit the most diversified forms and habits—one set of species being adapted by their structure for one set of functions in nature, and another set, very closely allied, for an opposite sphere of action. Thus the Histeridæ—small black beetles well known to English entomologists, most of whose species are short and thick in shape and live in the dung of animals—are most diversified in structure and habits in the Amazons region; nevertheless, all the forms preserve in a remarkable degree the essential characters of the family. One set of species live in dung; most of these are somewhat cubical in shape, the head being retractable within the breastplate, as in the tortoise. Another group of Histeridæ are much flatter in form, and live in the moist interior of palm-tree stems; one