STRUCTURE OF INSECTS. 293 



activity and power, derived from their augmented 

 length, and the more distinct lever-like forms of the 

 pieces which compose them. These pieces (see 

 Fig. 150) are named, from their supposed analogy 

 to the divisions of the limbs of the higher orders of 

 vertebrated animals, the haunch (h), the trochanter 

 (t), the femur (f), the tibia (s), and the tarsus (r). 

 In general the femur (or thigh) has nearly a hori- 

 zontal, and the tibia (or leg) a vertical position, 

 while the whole tarsus (or foot) is applied to the 

 ground. 



The haunch (h), which is supposed to correspond 

 to the hip bone of quadrupeds, is a broad, but very 

 short truncated cone. The mode of its articulation 

 with the trunk is very various : sometimes it is 

 united by a ball and socket joint, as in the Curculio 

 and Cerambyx ; and it then has, of course, great 

 freedom of motion : at other times the joint is of 

 the hinge kind, as in the Melolontha. The tro- 

 chanter (t), and the femur (f), though in reality 

 distinct pieces, are usually so firmly united as to 

 compose only one division of the limb. The arti- 

 culation of this portion with the haunch is always 

 effected by a hinge-joint. Joints of this description, 

 when formed, as they are in insects, by the apposi- 

 tion of two tubular pieces, are constructed in tlie 

 following manner. One of the tubes has, at the 

 end to be articulated, two tubercles, which project 

 from the margin, and are applied to the adjacent 

 end of the other tube, at two opposite points of its 

 circumference ; the line which passes through these 

 two points being the axis of motion. On the side 

 where the flexion is intended to be made, both 

 tubes are deeply notched, in order to admit of their 



