plant-house; alryrodes. , 135 



From this point it passes posteriorly to the sixth abdominal seg- 

 ment where it turns and runs anterioi^ly again to the first abdom- 

 inal segment; here it turns about again and joins the hind-intes- 

 tine which runs posteriorly to open on the dorsal surface of the 

 eighth abdominal segment at the vasiform orifice. The salivary 

 glands are small, nearly spherical organs, located in the dorsal 

 part of the prothorax. They are made up of a small number of 

 large . secreting cells. Coming from each gland is a small duct 

 which unites with its fellow just posterior to the brain in the 

 median line. 



Muscular System. See Fig. 51. The muscles of the body are 

 arranged in three chief systems. First : the intersegmental mus- 

 cles running between the segments for the whole length of the 

 body. These muscles are attached to the folds of the integu- 

 ment at the joints between the segments. Second : the muscles 

 of the wings, which are arranged in two sets, the elevators and 

 the depressors. The elevators are attached at their ventral ends 

 to ridges on the integument of the ventral wall of the two poste- 

 rior thoracic segments, and at their dorsal ends to the wings. 

 The depressors of the wings are two large muscles situated 

 in the dorsal part of the thorax, attached to the lateral and 

 dorsal walls of the thorax, and to a deep median ventral pro- 

 longation of the dorsal integument of the thorax. Third : the 

 muscles of the legs. These muscles are in part attached at the 

 dorsal ends to the dorsal wall of their respective segments, and in 

 part to the ventral median ridge. The ventral ends of both sets of 

 muscles are inserted in the walls of the femur of the leg to which 

 they are attached. There is a small set of muscles for moving 

 the mouth parts, which are attached dorsally to the dorsal and 

 lateral walls of the head and prothorax. In the posterior end of 

 the abdomen there is a set of small muscles which move the 

 ovipositor. 



Nervous Systeju. See Fig. 51. The nervous system is very 

 much concentrated. It consists of the brain and a ventral 

 ganglionic mass. The brain is quite complicated although of 

 rather small size. The cerebral hemispheres are very promi- 

 nent, standing above the other positions of the brain. The optic 

 lobes are small, hidden beneath the cerebal portion of the brain. 

 The optic tracts are well developed. They appear as a pair of 



