804 INSECTA. 
and which Latreille calls a spurigus proboscis ; and in regard to this organ 
Lamarck considers the Hymenoptera as intermediate between the gnawers 
and suckers. Among the insects which feed on fluids, or which extract their 
food by suction, the organs of manducation appear under two modifications 
In the first, the mandibles and jaws are replaced by minute lamina, in the 
form of sete, composing by their union, a kind of sucker (haustellum) which 
is received into a sheath, the substitute for a lip, either cylindrical, conical, 
or jointed, termed the rostrum or beak in the Hemiptera, or membranous 
and fleshy, terminated by two lips, termed the trunk or prodoscis, in the 
Diptera. The labium is triangular or conical, and covers the base of the 
sucker. In the second modification, the mandibles are excessively small, 
and in the form of a tubercle, more or less triangular, furnished with cilix 
on the internal margin; the lip is only distinguished by the presence of 
palpi; the jaws acquire an extraordinary length, and unite to form a probos- 
cis or tongue, (Jingua,) rolled up in a spiral form. Interiorly, this tongue is 
provided with three canals, of which the intermediate is the conduit of the 
nutritive juices; and at the base of the filaments isa minute palpus. The 
mouth of the Lepidoptera is an instance of this construction. 
The trunk or ¢horax is that part of the body which unites the head to the 
abdomen, and to which are attached the organs of locomotion. It is form. 
ed of three segments, each with a pair of feet; but in the winged insects 
the upper sides of the last two segments also form points of attachmen: 
for the wings. The term thorax has been given to the upper surface of thy 
trunk, and that of breast, to the opposite face below. The middle part ol 
the breast between the feet, is the séernwm, and the portion between the at- 
tachment of the wings, generally triangular, and sometimes very large, is 
named the shield, or scwtellum. The anterior segment of the thorax, in a 
great many winged insects, is much larger than the other segments, and 
separated from the second, by a very marked articulation; in others it is 
extremely short, and has the appearance of a collar, while the two follow- 
ing segments, of greater size, are internally united, and form a rounded mass, 
distinct from the abdomen. In both these cases, the large naked portion 
receives the name of thorax. 
The insects of the first three orders have but one species of locomotive 
organs, and only proper for walking; others have, also, wings to the number 
of four; and the posterior extremity of the thorax is furnished, in those 
which have only two wings, with two appendages, one on each side, termed 
poisers or balancers, (halteres,) and often other appendages in the form of 
spoonlike scales, (sguamule,) or winglets. 
The wings (ale) are membranous, elastic, gererally transparent, and 
attached to the upper sides of the thorax. The ribs or nerves, more 
or less numerous, which run through them, form sometimes a net-work, 
sometimes anastomosing veins. In wasps and bees, these wings, four 
mm number, are naked and transparent; in butterflies, they are cover- 
ed with minute scales, resembling fine powder, and embellished with 
