22 
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III 
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as compared with the body, is used as a character in describing 
genera and species, in some not extending, when pressed up against 
the breast, to the base of the middle legs, while in others, as various 
species of Lachnus , and Schizoneura , it extends beyond the base ot 
the hind legs sometimes nearly or quite to the tip of the abdomen, in 
quercus , Stomaphis (an exotic species) it is nearly twice the lengt 
of the insect. The base of the beak is the part by which it is joined 
to the head, the tip or apex the other extremity. 
Antenna .—The jointed bristle-shaped appendages which arise from 
the upper part of the head, and are sometimes improperly, termed 
horns. Although subject to less variation than what is found in some 
other orders, yet the differences are sufficient to furnish important 
generic characters. They vary in length from twice the length ot the 
entire body or even more, to but little more than that of the hea^ , 
and in the number of joints from seven to three, never exceeding the 
former and never less than the latter in the adult state. . I he. typica 
form is setaceous or bristle-like, and the widest variation is but a 
modification of this type. Throughout the family, as a rule whic 1 
has but few exceptions, the two basal joints are shorter and thicker 
than those which follow; the third is usually longest, though in Sipho- 
nophora and one or two other genera, the seventh sometimes equa s 
and even exceeds it; in these genera the latter resembles a slender bristle, usu¬ 
ally making a sudden offset at its junction with the sixth the articu¬ 
lation being always indistinct between these two joints. . In. Lachnus 
and some allied ' genera which are often classed as .six-jomted, the 
sixth is furnished with a spur at the tip which is evidently a rudi¬ 
ment of the seventh, but, as in the others, the articulation between the 
two is not apparent. Iu the five-jointed antennae of the.subterranean 
species, the fifth (see fix) is but a minute almost imperceptible 
tubercle. 
In the seven-jointed antennae, the last is often imbricated, sometimes 
it and other joints are partially surrounded by minute rings; the third 
ioint of the winged specimens is also often marked with little cncu ar 
pustules or hollow tubercles which are supposed by some entomologis s 
to be in some way connected with the sense of hearing. 
In Siphondphora and one or two other genera, these organs are situ¬ 
ated on short frontal tubercles; while in all the other genera they 
articulate directly with the head without the intervention of a tubercle. 
The larvae, and often the pupae, especially of the seven-jointed 
species, lack one or two antennal joints, a fact that should always be 
taken into consideration in describing or determining species, the 
addition takes place not by the growth of new joints at the tip, but. 
bv divisions usually of the third, or at least by a division of some 
one of the joints between the second and sixth, but from mv obser¬ 
vations I think it is chiefly by divisions of the third. 
Front or Vertex .—That part of the head between the antennae. It 
is sometimes grooved, sometimes flat and in other species convex. 
Eyes .—These are usually very distinct and prominent during the 
entire life of the insect, in fact they may often be seen m the em¬ 
bryo before it has left the parent; but in some ot the subterranean 
species these important organs are wanting. In many winged speci- 
