132 Invertebrate Zoology. 



The Muscular System. - - Lying either side of the heart 

 are the longitudinal abdominal muscles. The thorax con- 

 tains several bundles of alary muscles. Are those which move 

 the fore-wings separate from those which move the larger 

 posterior wings ? Fat-bodies may be found forming a loose 

 tissue throughout the cavity of the abdomen. 



The Respiratory System. The external openings of 

 the respiratory organs, or trachece, have been already noted. 

 They will be found to lead, within the body- cavity, to a 

 many-branched system of tubes which convey the air to the 

 tissues, as has already been observed in the caterpillar. 



The Reproductive System. The reproductive gland 

 rests in the upper part of the abdominal cavity. The ovary 

 is a bilateral organ which is continued posteriorly into a pair 

 of oviducts. The oviducts pass to the lower side of the 

 abdomen, where they unite and form the vagina. The vagina 

 opens to the exterior between the ventral pieces of the 

 ovipositor. Slightly above and anterior to the external open- 

 ing of the vagina, the much smaller opening which leads 

 from the bursa copulatrix will be found. The bursa is a 

 small sac which receives the spermatozoa. It is situated 

 beneath the rectum. 



The Digestive System. The (esophagus leads into a 

 large crop which extends from the mesothorax to the anterior 

 part of the abdomen. Lying laterally to the crop are the 

 branched salivary glands, the ducts of which may be traced 

 to their openings into the mouth. In the abdomen the crop 

 opens into the stomach which extends over half the length of 

 the abdominal cavity. The stomach opens into the intestine. 

 The gastric cceca are a series of pouches which lie parallel to 



