150 MORPHOLOGY OF INVERTEBRATE TYPES 



of the abdomen in a gravid female is due merely to a stretching 

 of the interarticular cuticle to its full capacity. The grasshopper 

 has an endoskeleton in the shape of the so-called tentorium in the 

 head and of furculce in the thorax. These structures are simply 

 apodemes or infoldings of the integument and serve for the 

 attachment of muscles. 



Muscular system. The muscular system shows clearly 

 the segmented nature of the grasshopper in the abdomen. In 

 the rest of the body the muscles are highly differentiated and 

 specialized. Of interest are the heavy muscles of the two pairs 

 of wings in the thorax and the muscles of the ovipositor in the 

 abdomen. Very powerfully developed are also the muscles of 

 the mandibles and those of the third pair of legs which are 

 adapted to jumping. 



Digestive system. The alimentary canal of the grass- 

 hopper is clearly divided into three portions, the foregut, the 

 midgut, and the hindgut. The foregut begins with the mouth 

 which is provided with mouth parts in the shape of an upper lip, 

 a pair of mandibles, a pair of maxillae, and a lower lip with the 

 hypopharynx, all except probably the upper lip being true ap- 

 pendages. The pharynx occupies the greater part of the head 

 and leads into the oesophagus which runs backward forming a 

 large crop or ingluvies in the meso- and metathoracic somites. 

 The last section of the foregut is the gizzard or proventriculus 

 which in other insects is very well denned, but which in the case 

 -of the American locust is not externally recognizable except 

 as the end portion of the crop. The midgut or ventriculus ex- 

 tends back into the seventh abdominal segment. It receives 

 eight double gastric cceca immediately behind the foregut. 

 These cceca are arranged so that one arm of each ccecum is 

 directed forward and the other backward. The end of the midgut 

 is marked by numerous malpighian tubes, beyond which the 

 hindgut begins. The first section of the hindgut is called ileum 

 and is comparatively large. Near the end of the abdomen it is 

 constricted and the much smaller colon rises in a curve. The 



