53 



larger masses of fat have been removed, and study the ental 

 layer of muscles of the dorsal wall of the abdomen. 



On each side of the heart and ectad of the wings of the 

 heart, there are great bands of longitudinal muscles, occupy- 

 ing the space between the heart and the prominent muscles 

 that extend dorso-ventrad on the sides of the body. Of the 

 longitudinal, dorsal muscles there are two sets on each side. 

 The wider set, which lies near the heart, may be termed the 

 gr-eat-dorsal-recti-muscles ; the narrower set, which lies be- 

 tween the great-dorsal-recti-muscles and the dorso-ventral 

 muscles of the sides of the body, may be termed the small- 

 dorsal-recti-muscles. 



Of the dorso-ventral muscles of the sides of the body, re- 

 ferred to above, there are two large bundles on each side of 

 •each segment they are situated near the union of the seg- 

 ments. 



Between the lateral muscles and the cut edge of the speci- 

 men (the dorsimeson) lie the great - ventral - recti -muscles. 

 These differ from the great-dorsal-recti-muscles in being 

 somewhat oblique (this is shown better in specimens opened 

 on the back). 



Make a drawing of the third, fourth, and fifth abdominal 

 segments representing the muscles mentioned above. 



Carefully remove the recti muscles in one or two abdomi- 

 nal segments and note that ectad of them are many muscles 

 extending obliquely in various directions. The study of 

 these oblique muscles will be omitted in this course. 



