Longicornia. | LONGICORNIA. . 215 
or about a fifth of the whole number previously known ; since the 
latter year a considerable number have been described, and a large number 
of new genera and species will be found enumerated in the Zoological 
Records for the last four years as described by Mr. H. W. 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 
obseure groups, but they are so conspicuous by reason of their large and 
elegant shape and colouring and their very long antenne that they are 
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 larve 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- 
timbered 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 larvee, 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 and 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 eroup:—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, 
emarginate, rarely entire, sometimes entirely divided ; antennz usually 
very long, but occasionally (e.g. in Rhagium) 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; maxilla: with two lobes, one being occasionally 
obsolete, mandibles strong, labial palpi 3-jointed ; 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, tibi generally furnished with spurs at apex; tai si 
pseudo-tetramerous, 5-jointed, but with the fourth joint very small and 
connate with the fifth, which is slender, third joint bilobed, joints 1-3 
except sometimes on the posterior pairs) usually furnished with thick 
pubescence underneath (which, however, is sometimes absent on the 
