ANATOMY AND PHYSIOLOGY 51 
Some ambiguity attends the use of these terms. Thus some 
writers use the term apodemes for apophyses and others apply 
the term apodeme to any of the three 
Fic. 60. 
kinds of ingrowths. 
Legs.—In almost all adult insects and 
in most larve each of the three thoracic 
segments bears a pair of legs. The leg 
is articulated to the sternum, episternum 
and epimeron and consists of five seg- 
ments (Fig. 60), in the following order : 
coxa, trochanter, femur, tibia, tarsus. 
The coxa, or basal segment, often has a 
posterior sclerite, the trochantine.t The 
trochanter is small, and in_ parasitic 
Hymenoptera consists of two subseg- 
ments. The femur is usually. stout and 
conspicuous, the tibia commonly slender. 
The tarsus, rarely single-jointed, consists 
usually of five segments, the last of which 
bears a pair of claws in the adults of 
most orders of insects and a single claw 
in larve; between the claws in most 
imagines 1S a pad, usually termed the Leg oieeede ce 
pulvillus, or empoduun. soma calidum. c, coxa; 
5 cl, claws; 7, femurs: 7s; 
Adaptations of Legs.—The legs ex- spur; #45, tarsal seg- 
hibit a great variety of adaptive modifica- ments> %, tibia; #, 
‘ . = 2 ; trochanter. 
tions. A walking or running insect, as a 
carabid or cicindelid beetle (Fig. 62, 4) presents an average 
condition, as regards the legs. In leaping insects (grasshop- 
pers, crickets, Haltica) the hind femora are enlarged (B) to 
accommodate the powerful extensor muscles. In insects that 
make little use of their legs, as May flies and Tipulidz, these 
appendages are but weakly developed. The spinous legs of 
* But on account of the ambiguous use of this last term, the name meron 
(Fig. 61), proposed by Walton, is to be preferred. 
