ANATOMY AND PHYSIOLOGY 



tb 



notably in the mole-cricket (Fig. 62, E), in which the fore tibia has some 



resemblance to the human hand, while the tarsus and tibia are remarkably 



adapted for cutting roots, after the manner of shears. 



The Scarabaeidae have fossorial legs, the anterior tarsi of 



which are in some genera reduced (F) or absent; they 



are rudimentary in the female (G) of Phanceus carnifex 



and absent in the male (H), and absent in both sexes 



of Deltochilum. Though females of Phanaus lose their 



front tarsi by digging, the degenerate condition of 



these organs cannot be attributed to the inheritance 



of a mutilation, but may have been brought about by 



disuse; though no one has explained why the two sexes 



should differ in this respect. Many insects use the 



legs to clean the antennae, head, mouth parts, wings 



or legs; the honey bee (with other bees, also ants, 



Carabidae, etc.) has a special antenna-cleaner on the 



front legs (Fig. 264, Z>), which is described, with 



other interesting modifications of the legs, on page 211. 

 Indeed, the legs serve many such minor purposes 



in addition to locomotion. They are generally used 



to hold the female during coition, and in several genera 



of Dytiscidae (Dytiscus, Cybister) the male (Fig. 62, /) 



has tarsal disks and cupules chiefly on the front tarsi, 



for this purpose. Among other secondary sexual pecu- 

 liarities of the legs may be mentioned the tibial brushes 



of the male Catocala concumbens, regarded as scent 



organs, and the queer appendages of male Dolicho- 



podidae that dangle in the air as these flies perform their dances. 



The pulvillus is commonly an adhe- 

 sive organ. In flies it has glandular hairs 

 that enable the insects to walk on smooth 

 surfaces and to walk upside down; so 

 also in many beetles and notably in the 

 honey bee (Fig. 63) ; in this insect the 

 pulvillus is released rapidly from the sur- 

 face to which it has been applied, by 

 rolling up from the edges inward. 



Sense organs occur on the legs. 

 Thus tactile hairs are almost always 



present on these appendages, while auditory organs occur on the front 



t* 



FIG. 60. Leg of a 

 beetle, Calosoma cali- 

 dum. c, coxa; cl, 

 claws; /, femur; s, 

 spur; / 1 -/ 5 , tarsal seg- 

 ments; tb, tibia; tr, 

 trochanter. 



r es 



em 



FIG. 61. Left hind leg of Bittacus. 

 c,coxa genuina; em,epimeron; es, epi- 

 sternum; /, femur; m, meron; /, tro- 

 chanter. 



