SENSE OF TOUCH. 9 



beetle (Timarcha tenebricosa, MEGERLE), this struc- 

 ture of the feet is very obvious without the aid of a 

 glass, which is required in observing the palms of the 

 two-winged flies (Diptera). 



In some other beetles, again, whose horny covering 

 would seem to preclude them from possessing the 

 means of touch over the surface of their body like the 

 softer animals, and which even have their legs equally 

 horny and stiff, we may observe, that a beautiful pro- 

 vision is made for the sense of touch in a long, many- 

 jointed, flexible claw at the termination of the foot. 

 This is particularly remarkable in the common dung 

 beetle (Geotrupes stercorarius), in which the flexibi- 

 lity and easy motion of the jointed claw contrasts 

 strikingly with the apparently awkward stiffness of 

 the other joints, and indeed of the whole body. 



According to the greater number of naturalists, 

 however, the two chief organs of touch in insects are 

 the antenna? and palpi, both of which have been in 

 popular language termed feelers. Latreille calls the 

 palpi antennules*. Leaving the antennae to be dis- 

 cussed in our chapter on Hearing, we shall only 

 at present attend to the palpi, which are usually 

 four in number. These organs are small and gene- 

 rally cylindrical, consisting of from one to six joints, 

 one palpus being implanted in each of the two lower 

 jaws, and the remaining two being attached to the 

 lower lip, as exhibited in p. 43, fig. a. The former, 

 or upper pair, are, in most cases, a joint longer 

 than the under, so as that they may all four, when 

 bent down, reach to the ground at the same time. 

 They are most commonly smooth, and end in a softish 

 point ; but in some cases they are covered with hair 

 (Copris, Cicindela, fyc.). The only organs, in the 

 higher animals, which seem analogous to these, are the 

 whiskers (Vibrissce) in the cat, the seal, and the night- 

 * Regne Animal, iv. 301, edit. 1829. 



