Lomjicornia.] I.ONGICORNIA. 215 



or about a iifth of the whole number previously known ; since the 

 latter year a considerable number have been described, and a large number 

 of now genera and species will be found enumerated in the Zoological 

 Records for the last four years as described by Mr. H. \V. Bates in the 

 Biologia Centrali- Americana, and by other authors ; it is not, perhaps, 

 that these insects are more numerous than those belonging to more 

 obscure groups, but they are so conspicuous by reason of their large and 

 elegant shape and colouring and their very long antennae that they arc 

 much more likely to be seen by an ordinary observer, and are among the 

 insects that are most frequently brought to collectors in tropical 

 countries by natives sent out to search for objects of natural history, 

 who, unless trained, are almost certain to neglect the less conspicuous 

 forms. 



By far the largest number of the species belonging to the group are 

 found in the tropics, and, as the larvae are invariably wood-feeders, it is 

 obvious that those districts will be most rich in members of the group 

 which are most thickly clothed with virgin forests, and probably no 

 other portion of the world contains a larger number than the densely- 

 ti inhered Amazon basin ; in these great forests the Longicornia play a 

 very important part in the economy of nature ; as soon as a tree dies 

 and begins to decay, their larvae, which are very often of great size, 

 attack it and bore it through and through ; the work of boring from 

 their large galleries is then taken up by various smaller species of wood- 

 boring Coleoptera, and free access is thus given to the rain aud moisture, 

 which soon reduce the trunks to a pulp, and cause them not only to 

 disappear, but to act as manure to those trees that take their places; 

 were it not for the agency of these insects, the forests, in course of time, 

 would be blocked up and gradually disappear. 



The following are the chief characteristics of the group: Form elongate, 

 usually more or less depressed, with the elytra almost always broader 

 than the thorax, usually considerably so ; head variable, eyes, as a rule, 

 enmrginate, rarely entire, sometimes entirely divided ; antenna; usually 

 very long, but occasionally (e.g. in Rliayium) short, inserted either in 

 front of or between the eyes, not clavate, filiform or setaceous, rarely 

 serrate or pectinate, in exotic genera occasionally ornamented with 

 brushes of hair ; maxillae with two lobes, one being occasionally 

 obsolete, mandibles strong, labial palpi 3-joiuted ; thorax rarely mar- 

 gined, sometimes denticulate at sides ; elytra, as a rule, covering 

 abdomen, but sometimes abbreviated ; abdomen composed of five free 

 ventral segments, a sixth being sometimes visible ; legs variable, some- 

 times rather short and stout, sometimes very long and slender, femora 

 often clavate, tibiae generally furnished with spurs at apex ; tarsi 

 pseudo-tetramerous, 5-jointed, but with the fourth joint very small and 

 connate with the fifth, which is slonder, third joint bilobed, joints 1-3 

 (except sometimes on the posterior pairs) usually furnished with thirk 

 pubescence underneath (which, however, is sometimes absait on the 



