x] 



THE BODY-WALL AND MUSCLES 



205 



more easily seen than in the striated muscles of Vertebrates. 

 Further, whereas the nuclei of the leg-muscle fibres are situated 

 peripherally, those of the wing-muscle fibres are placed centrally, 

 and are much larger and more elongated. 



The muscles may be attached, both at origin and insertion, 

 either directly (as in the case of the body-muscles to the hypo- 

 dermis) or by means of a tendon, i.e. a chitinous ingrowth 

 from the cuticle. The ordinary tendon is conical, receiving the 

 muscle-fibres into its broad hollow end; it is of a pale colour. 

 Special strong tendons, of a dark colour and peculiar shape, occur 

 in connection with certain muscles, 

 notably most of the wing- muscles. 

 Such tendons are known as cup- or 

 cap-tendons, from their shape, which 

 is either in the form of an inverted 

 cup, a skull-cap, a flattened pyramid 

 or wedge. The stalk of the tendon 

 may be either long or short. 



The development of the mus- 

 cular system in the Dragonfly is 

 very great. Even a brief account 

 of all the muscles in its body would 

 take up far more space than a 

 volume of this size can afford. It 

 will be sufficient here to tabulate 

 the principal muscles of the various 

 regions of the body, giving their 

 names, their places of origin and 

 insertion, and any further details 

 that may be of interest to the 

 student. The use of Latin names 

 has been avoided [io, 22. 84, 120, 121, 184]. 



Fig. 90. Section parallel to notal 

 plane through synthorax of Isch- 

 nura aurora Br. ( x 20). Muscles 

 as in fig. 89, except ta 1 = tendon 

 of ac 1 . ao aorta ; cut cuticle ; dc 

 dorsal carina; dt dorsal tracheal 

 trunk ; hs humeral suture ; hy 

 hypoderm; Zs 2 second lateral 

 suture; nv nerve-cord; ce oeso- 

 phagus; tr trachea. Original. 



