1920] Dii Porte: Muscular System of Gryllus 27 



(b) Dorsal. 



XIX. The First Pronotal Muscle (Fig. 20). From the 

 posterior edge of the pronotum near the median line, into the 

 inflexed posterior border of the neck membrane. [109]. 



19, 20. The Third Pronotals (Figs. 20, 21). From the 

 first intersegmental sclerite into the median ridge of the 

 pronotum. [Ill, 110]. 



DORSOVENTRAL MUSCLES. 



(a) Tergo-sternal. 



21, The Prothoracic Intersegmental Muscle. From the base 

 of the furca into the outer angle of the first intersegmental 

 sclerite. Rotator of the thorax. [112]. 



(b) Noto-subcoxal. 



22, The First Dorsoventral Muscle of the Prothorax (Fig. 20). 

 From the pronotum immediately behind the distal end of the 

 epimeron into the trochantin by a long flat tendon. A strong 

 conical muscle. An extensor of the coxa.* [113]. 



(c) Noto-coxal. 



23, 23a. The Second Dorsoventral (Fig. 20). Origin, in 

 the pronotum immediately above the distal end of the pleuron 

 usually with two (sometimes three) adjacent heads; insertion 

 into the posterior edge of the coxa by a long thin tendon. 

 A flexor of the coxa. [114]. 



24, 24a. The Sixth Lateral (Fig. 21). From the posterior 

 side of the pronotum into the latero-caudal edge of the coxa 

 by a broad tendon. Two heads — 24 is a stout-bellied muscle 

 while 24a is quite slender. Flexor of the coxa. [121]. 



(d) Noto-trochanteric. 



25, 25a-25e are the six heads of a complex muscle inserted 

 by a common tendon into the inner angle of the base of the 

 trochanter. Together they form the extensor of the femur. 

 The origins of the various heads are noted in their proper places 

 below. 



* When the coxa is pulled backwards it moves upwards towards the sternum. 

 A forward pull moves it also downwards away from the body. I have designated 

 the muscles which bring about these motions as flexors and extensors respectively, 

 reserving the terms adductor and abductor for those muscles which pull the coxae- 

 inwards towards each other and outwards away from each other. 



