INTERNAL ANATOMY. 



The internal structure of the locust is somewhat 

 difficult to make out, owing to the small size of the 

 animal. Fig. 14, p. 36, from Edward Burgess's origi- 

 nal drawings, gives the anatomy of our common red- 

 legged species, Caloptenus feniur-i-ubrum. 



7n is the mouth ; sal, the salivary glands. These glands 

 empty their alkaline secretion into the mouth near its base. 

 The oesophagus {oe) leads from the mouth to the crop (Fig. 

 14, crop). It is in the crop that the "molasses,'^ or un- 

 digested food, originates. The crop passes into the small 

 gizzard, which is between the crop and true or chyle- 

 stomach (Fig. 14, stomach) ; from the forward end of the 

 latter arise six gastric cseca (Fig. 14, caecum). These are 

 dilatations of the chyle-stomach, and " probably serve to 

 present a larger surface from which the chyle may escape 

 into the body cavity and mix with the blood, there being 

 in insects no lacteal vessels or lymphatic system.'" The 

 stomach passes into the intestine (ileum) and colon (Fig. 

 14, colon) ; the latter suddenly expands into the rectum 

 (Fig. 14, rectum), which is supplied with six rectal glands 

 (see Figure) . At the posterior end of the stomach arises 

 the urinary tubes {tir, cut off, leaving the stumps) ; these 

 correspond in function to the kidneys of vertebrates. The 

 heart (Fig. 14; PL II., Fig. 16, heart, p. 38) is the en- 

 largement of a blood-vessel which extends along the dor- 

 sal side of the body. The "brain,'' or supra-oesophageal 

 ganglion (Fig. 14, sP), gives off nerves to the antennae {af) 



