1920] Hickernell: Digestive System of Cicada 227 



confined to the metathorax. The posterior portion (Figs. 1, 2 

 and 3, pc) has its anterior boundary at the beginning of the first 

 abdominal segment. Its extent in the posterior direction is 

 variable and this variation will be discussed later but in extreme 

 cases its posterior boundary is found as far back as the sixth 

 abdominal segment. 



The dorsal wall of the anterior crop is concealed by a winding 

 mass of tubes which will be described later. For want of a 

 better name this mass will be called the "internal gland," fol- 

 lowing the terminology of Lubbock ('59). Although Lubbock 

 probably intended his designation to include more than it does 

 in the present case, it seems expedient to continue the use of 

 the term in connection with that part of the complex made by 

 the ascending intestine and malpighian vessels just above the 

 anterior crop. In shape, this complex of crop and internal 

 gland usually appears as an elongated spheroid, but it may be 

 bent upwards so as to look in side view like an inverted U. 

 The diameter of the entire structure is roughly five times that 

 of the esophagus. Posteriorly it narrows and apparently 

 connects with the large posterior crop. 



The descending intestine arises from the left side of the 

 internal gland near its anterior margin. In a gross dissection 

 this tube sometimes appears to be a continuation of the esoph- 

 agus but sections of this region show it to be otherwise, as will 

 be explained later. It is only about half the diameter of the 

 esophagus and is characterized by a gray color which is uniform 

 throughout its whole extent. It follows the ventral margin of 

 the anterior crop but leads in a general posterior direction. The 

 windings of this tube are confined in most cases to the dorsal 

 half of the insect. At the boundary between the sixth and 

 seventh abdominal segments it winds upon itself in such a way 

 as to make a knot (Figs. 1, 2 and 3, kk). From this knot or 

 coil the tube emerges and joins the rectum which latter narrows 

 as it passes posteriorly until it ends in the anal opening. 



The posterior end of the internal gland receives another tube 

 (Figs. 1, 2 and 3, at) which is distinguishable from the one pre- 

 viously described both as to its color and also with regard to 

 the course it takes. Its color is noticeably yellow, a condition 

 as will be shown later, traceable to the precence of cytoplasmic 

 inclusions in the epithelium of its walls. This yellow tube, the 

 ascending intestine, also runs in a sinuous fashion over the sur- 



