MUSCULAR SYSTEM. 317 



by a series of internal muscles, attached to the internal 

 surface of the external covering of the animal. Of the 

 extent of this system of muscles, some idea may be en- 

 tertained, when it is stated that Lyonnet discovered 4061 in 

 the caterpillar of the goat-moth, 228 being attached to the 

 head, 164/ to the body, and 2186 to the intestines; where- 

 as, in the human body, only 529 have been discovered ; so 

 that this insect possesses nearly eight times as many muscles 

 as there are contained in the human frame. This, however, 

 will not appear so extraordinary, when the greater number 

 of legs, &c. in the insect are remembered. 



The construction of insect muscles is similar to those of 

 the higher animals, each being formed of muscle and of 



tendon ; the former is 

 fleshy, whilst the lat- 

 ter, which forms the 

 coating and extremi- 

 ties of the muscle, is 

 firm, and not liable to 

 contraction. Accord- 

 ing to Lyonnet, the 

 muscles are composed 

 of manyparallel bands, 

 consisting of bundles 

 of fibres enveloped in 

 separate membranes ; 

 these fibres appearing 

 to be twisted in a 

 spu-al direction. These 

 muscles are attached 

 at one end to the various processes of internal surface 

 of the outer covering, which serves as their fulcrum, 

 and the other end is attached to the organ to be moved. 

 The size of muscles is proportioned to the movements 



E E 3 



Fig. 151, Dorsal muscles of the anterior segments of 

 the caterpillar of Cossus. 



