222 TOPOGRAPHICAL AX ATOMY OF THE 



great pectoral sclerite. Hammond [78] considers, I think cor- 

 rectly, that the origin of the muscles of the anterior coxa from 

 the paratreme, which he calls the humerus, is an additional 

 argument in favour of its being part of the prothorax. 



The corresponding muscles of the two posterior legs are also 

 four in number — one which arises from the lateral region of the 

 tergum, outside the sterno-dorsal muscles ; two from the corre- 

 sponding entothoracic apophyses ; and a fourth from the 

 lateral plate of the sternum. Their joint action is circumduc- 

 tion of the limb. There are also several small bands of 

 muscle in the interior of the coxa, the general direction of 

 which is transverse. They are inserted into the trochanter. 



The muscles of the femur are a flexor and an extensor. 

 Those of the anterior limbs arise within the coxal joint, which 

 they almost fill ; and those of the two posterior pairs of limbs 

 arise from the entothorax, with the coxal muscles. 



There is also a flexor and an extensor of the tibia , which arise 

 within the femur; these are bipenniform muscles. A third 

 short bipenniform muscle, the long flexor of the tarsu s, ending 

 in a long tendon, also arises high up in the femur. This 

 is inserted into the internal process of the planta, and gives 

 off a slip to the plantar surface of each tarsal joint, which 

 is inserted into the syndesmosis. Straus Durckheim described 

 no corresponding muscle in the Cockchafer, nor do I remember 

 seeing any description of such a umscle in any other insect. 



The tibia contains two bipenniform muscles — the flexor and 

 extensor of the first tarsal joint, which are similar to the flexor 

 and extensor of the tibia. There is also a smaller__j2auscle 

 between them, seen in transverse sections. This is perhaps 

 a long extensor of the tarsus, but I have not been able to 

 follow the tendon to its insertion. 



There are also short extensors and flexors of the tarsal joints, 

 and of the claws and pads, which extend from each phalanx to 

 the next below. The terminal joint contains the muscles of the 

 claws and pads. 



5. The Respiratory Muscles. — I have applied this term to the 

 small muscles which control the valves of the spiracles, and 



