'226 Annals Entomological Society of America [Vol. XIII, 



IV. The Digestive Tube in the Adult Male Insect. 



The male has been chosen as the subject for more detailed 

 description because of the fact that in this sex particularly 

 more doubt has been expressed as to the completeness of the 

 enteric canal. 



In the cicada it is difficult to recognize the boundaries of the 

 fore, mid and hind guts. Not only do these parts fail to con- 

 form in their gross anatomy to the relatively simple divisions 

 as found, for example, among the Orthoptera, but their his- 

 tological structure also fails in most cases to correspond with 

 that of the more familiar forms. The puzzling relationship of 

 parts and the changes taking place in some of these parts during 

 the life cycle may be due to any or all of several factors, viz., 

 the nature of the liquid food ; the influence of food stored in the 

 body in the form of fat; or to the peculiar life history of the 

 insect. However, since most of the sap-sucking Hemiptera in 

 which the digestive apparatus has been described have some 

 similar peculiarities, no clue is obtainable from them as to the 

 significance of these conditions. That part of the following 

 description relating to the sequence of parts in the tube and to 

 their general relationships can best be understood by reference 

 to Fig. 3. This is entirely schematic and attempts to represent 

 none of the finer details of structure. 



The extreme anterior portion of the digestive canal is not 

 greatly different from that described for numerous other forms. 

 The long proboscis, containing a pair each of functional stylet- 

 like mandibles and maxillae, leads dorsally through the pharynx 

 into the narrow esophagus. The latter, when it reaches a point 

 midway between the dorsal and ventral surfaces of the animal, 

 turns at right angles and proceeds toward the posterior end. 

 The point where the esophagus changes direction is just 

 posterior to the boundary between the head and prothorax. 



The esophagus does not vary much in diameter throughout 

 its entire extent, (Figs. 2 and 3). It may, with little difficulty, 

 be followed in a properly dissected specimen, with the unaided 

 eye, and it is easily traced with a lens of low magnification. At 

 the line of division between the mesothorax and the metathorax 

 the esophagus empties into the crop. 



The crop is divided into two parts of unequal size. The 

 anterior part (Figs. 1, 2 and 3, ac) is the smaller and is usually 



