1920] Dii Porte: Muscular System of Gryllus 35 



THE MUSCLES OF THE LEGS. 

 (Plate V.) 



The various muscles of the coxa as well as the large extensors 

 of the femur which originate in the thorax have already been 

 described. The following muscles lie entirely within the leg 

 segments. 



(a) Coxo-trochanteric Muscles. 



The First Intracoxal Extensor of the Femur (Figs. 23 and 25, 



1 ext. fem.) is a stout muscle with slightly converging fibres. 

 It originates from the anterior side of the basal border of the 

 coxa and is inserted into the trochanter just in front of the 

 insertion of the large noto-trochanteric extensors. 



The Second Intracoxal Extensor of the Femur (Figs. 23 and 25, 



2 ext. fem.) is a conical muscle originating from the ventral edge 

 of the bas6 of the coxa and inserted by the same tendon as the 

 noto-trochanteric extensors into the ventral edge of the 

 trochanter. 



The Third Intracoxal Extensor of the Femur (Figs. 23 and 26, 



3 ext. fem.) originates from the posterior face of the coxa and 

 is inserted into the trochanter behind the insertion of the 

 noto-trochanteric extensor. 



The First Flexor of the Femur (Figs. 23 and 26, 1 fi. fem.) 

 originates in the dorsal edge of the coxa, and in the first and 

 second legs, is inserted by a tendon into the dorsal edge of the 

 base of the trochanter. In the hind legs it is inserted into the 

 base of the femur at the dorsal edge of the femoral opening. 



The Second Flexor of the Femur (Figs. 24 and 26, 2 fi. fem.) is 

 similar to the first in its insertion. In the pro- and mesothoracic 

 legs this flexor is a simple conical muscle, originating from the 

 ventral side of the basal end of the coxa and running diagonally 

 across the coxa. In the metathoracic leg the second flexor 

 is a more powerful multiceps muscle. One head originates 

 from the posterior face of the coxa, one from the ventral edge 

 of the anterior face, and three from the basal edge of the anterior 

 face. 



(b) Trochantero-femoral Muscles. 



The Fourth Extensor of the Femur (Fig. 25, 4 ext. fem.) is a 

 small muscle originating from the ventral side of the base of 

 the trochanter and inserted into the ventral side of the base of 

 the femur. 



