beetles, they are either pectinate or bipectinate, being in one case at least, that of the Australian Hepialid (_Abantiades argenteus_), tripectinate (Fig. 44), and in the dipterous (Tachinid) genus Talarocera the third joint is bipectinate (Fig. 45). In Xenos and in Parnus they may be deeply forked, while in Otiocerus, two long processes arise from the base, giving it a trifid shape. In dragon-flies and cicadæ, they are minute and hair-like, though jointed, while in the larvæ of many metabolous insects they are reduced to minute three-jointed tubercles. In aquatic beetles, bugs, etc., the antennæ are short, and often, when at rest, bent close to the body, as long antennæ would impede their progress. [Illustration: FIG. 43.—Different forms of antennæ of beetles: 1, serrate; 2, pectinate; 3, capitate (and also geniculate); 4–7, clavate; 8, 9, lamellate; 10, serrate (Dorcatoma); 11, irregular (Gyrinus); 12, two-jointed antenna of _Adranes cæcus_.—After LeConte. _a_, first joint of flagellum of antenna of _Troctes silvarum_; _b_, of _T. divinatorius_.—After Kolbe. ] [Illustration: FIG. 44.—Tripectinate antenna of an Australian moth. ] While usually more or less sensorial in function, Graber states that the longicorn beetles in walking along a slender twig use their antennæ as a rope-dancer does his balancing pole. [Illustration: FIG. 45.—Antenna of _Talarocera nigripennis_, ♂.—After Williston. ] Recent examination of the sense-organs in the antennæ of an ant, wasp, or bee enables us, he says, to realize what wonderful organs the antennæ are. In such insects we have a rod-like tube which can be folded up or extended out into space, containing the antennal nerve, which arises directly from the brain and sends a branch to each of the thousands of olfactory pits or pegs which stud its surface. The antenna is thus a wonderfully complex organ, and the insect must be far more sensitive to movements of the air, to odors, wave-sounds, and light-waves, than any of the vertebrate animals. That ants appear to communicate with each other, apparently talking with their antennæ, shows the highly sensitive nature of these appendages. “The honey-bee when constructing its cells ascertains their proper direction and size by means of the extremities of these organs.” (Newport.)