ANATOMY AND PHYSIOLOGY 



49 



tr 



mentary in the female (G) of Phan&us carnifex and absent in the male 

 (H)j 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 ex- 

 plained 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. 267, D), which is described, with other inter- 

 esting modifications of the legs, on page 229. 



Indeed, the legs serve many such minor pur- 

 poses in addition to locomotion. They are com- 

 monly used to hold the female during coition, 

 and in several genera of Dytiscidae (Dytiscus, 

 Cybister) the male (Fig. 64, 7) has tarsal disks and 

 cupules chiefly on the front tarsi, for this purpose. 



, es 



FIG. 62. Leg of a beetle, Calo- 

 soma calidum. c, coxa; cl, claws; 

 /, femur; s, spur; t l -t b , tarsal seg- 

 ments; tb, tibia* tr, trochanter. 



FIG. 63. Left hind leg of Bittacus. 

 c, coxa genuina; em, epimeron; es, 

 episternum; /, femur; m, trochantin; /; 

 trochanter. 



Among other secondary sexual peculiarities of the legs may be men- 

 tioned the tibial brushes of the male Catocala concumbens, regarded as 

 scent organs, and the queer appendages of male Dolichopodidae that 

 dangle in the air as these flies perform their dances. 



The pulvillus is commonly an adhesive organ. In flies it has glandu- 

 lar 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. 

 65) ; in this insect the pulvillus is released rapidly from the surface 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 tibiae of Tettigoniidae, Gryllidae and some ants. Finally, the 



