164 Mr. H. W. Bates on Longicorn 



greater extent than in other tropical forests in which I 

 have wandered. Twelve species of humming-birds feed 

 on the smaller insects ; and trogons, motmots, with a 

 great variety of other birds prey on the larger species. 

 It is to this incessant persecution, I have no doubt, that 

 the insect world owes the special means of protection, 

 the mimicry and disguises, which are so extensively 

 assumed ; some being provided with stings and offensive 

 flavours, and others mimicking these both in external, 

 appearance and movements." 



As Mr. Belt^s collections were thus made wholly in 

 the forest region of the lower levels, and contain no mix- 

 ture of the productions of the " tierra templada," or 

 temperate zone of elevation, which forms so uncertain an 

 element in collections from Mexico, and the Andean 

 regions of South America; they ought to furnish a satis- 

 factory means of comparing the insect fauna with that of 

 various distant portions of eastern tropical America, 

 such as the Amazons, South Brazil, &c. For, as 

 almost the whole Atlantic slope of the Continent, from 

 the southern to the northern tropic, is clothed with luxu- 

 riant forest, containing the same types of vegetation, 

 and having a similar warm humid climate ; and as, more- 

 over, there exists no effective barrier to distribution, it 

 becomes an interesting question how far the productions 

 of the different portions resemble, or differ from each 

 other. Prima facie, it would appear that the fauna ought 

 to be almost the same throughout the whole area; and if 

 there is great diversity, the causes of it form a problem 

 of great importance. In such inquiries, however, we 

 are always met, as regards . Entomology, by obstacles 

 caused by the fragmentary state of our knowledge. Some 

 districts have been well, and others only superficially, 

 worked. As regards Longicorn Coleoptera of Tropical 

 America, we have a further difficulty, in the circumstance 

 that a large number of species have been suffered to 

 remain undescribed in collections, or, if described, are 

 referred to wrong genera. At present, therefore, there 

 is little to be done, except to describe new genera and 

 species, and note some of the most obvious facts in the 

 relations of the various faunas. Happily, the termina- 

 tion of Lacordaire's great revision of the genera of 

 Longicornia enables us, at least, to refer the forms we 

 have to deal with, with much greater certainty than 

 before, to their natural place in the system. 



