that this is one of the uses to which they are eminently subservient.
Still, however, touch is only a secondary function of the latter; the generality of authors now agree in regarding them as the appropriate organs of hearing. When a beetle with long antennæ is suddenly surprised by a loud sound, it stretches these members outwards and holds them immoveable as if listening, and moves them carelessly again when the noise has ceased. They are two in number, in this, as well as in their prominent situation, corresponding to the ears of the vertebrata. On close examination a soft articulating membrane can be detected at their base, beneath which the antennal nerve is conducted; this may be considered as the last vestige of a tympanum, and the nerve alluded to, as an acoustic nerve. Viewed in this light, the stalk of the antennæ must be employed to collect the pulses or vibrations of the atmosphere and transmit them to the sensorium, an office for which their branched, plumose, and other delicate structures all tending to increase the extent of their surface, eminently fit them. This view receives strong confirmation from the circumstance of the auditory organ of the Crustacea being placed at the base of the antennæ, sometimes even in the radical joint. It has been well observed also that the organs in question are almost always very fully developed in such insects as emit sounds as a signal call to the sexes, a case in which hearing requires to be more than usually acute. Crickets, Grylli, and Cerambycidæ, may be given as
