OP INSECTS. 131 



food ; but when the part alluded to exists the crop 

 is furnished with interior glandular organs which se- 

 crete an active juice. These glands are most con- 

 spicuous among the tiger-beetles, (Cicindela) even 

 appearing in external rows on the obcordate shaped 

 crop. (Plate II. fig. 2, b.) With very few excep- 

 tions besides this, the surface of the crop is quite 

 smooth. These remarks, however, apply to this 

 part only as it appears among masticating insects; 

 in all other kinds, with the single exception of the 

 Hemiptera, it becomes (or there is substituted in its 

 place, according to the views we adopt regarding 

 its origin,) what has not improperly been called a 

 sucking-stomach. (Plate II. fig. 4, c.) Its function is 

 no longer to receive the alimentary substances trans- 

 mitted from the mouth, but to facilitate the rise of 

 the fluids from the mouth to the principal receptacles 

 of the alimentary canal. This it promotes by dis- 

 tending at the will of the insect, and thus rarifying the 

 air in its interior and acting as a kind of pump. It 

 presents various modifications of form in all the dif- 

 ferent tribes possessing it. The crop is succeeded by 

 the gizzard, (Plate II. fig. 2, c.) which may always be 

 recognised, when present, by having its internal sur- 

 face covered with teeth, spines, or horny ridges ; a 

 structure which eminently fits it, in connection with 

 its muscular, almost cartilaginous texture, for sub- 

 jecting the food to a more complete trituration than 

 it had previously undergone. It exists in all insects 

 that feed on hard substances, such as wood, bark, 

 &c., and iu all carnivorous kinds ; but not in those 



