210 CAEIPI. Chap. V. 



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 

 hebraeus, 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 (Chry- 

 soprasis), 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 Caripi, a few obser- 

 vations 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 

 Histeridse — 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 Ama- 

 zons 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 re- 

 tractable within the breastplate, as in the tortoise. 

 Another group of Histerida3 are much flatter in form, 

 and live in the moist interior of j)alm-tree stems ; one 



