112 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



organs. The position of these lobes between the mouth and the ad- 

 ductor apodemes of the mandibles strongly suggests that they are 

 rudiments of the postantennal appendages of the tritocerebral seg- 

 ment, which have otherwise not been observed in the adult of any 

 pterygote insect. 



THE STOM ODEUM 



At the upper end of the preoral cavity (fig. 41, PrC), anterior to 

 the base of the hypopharynx, and immediately behind the base of the 

 clypeus is the true mouth (Mth), or external opening of the stomo- 

 deum. The mouth of Dissostcira is a transverse aperture having 

 acute lateral angles, I)Ut without definite " lips," for the epipharyngeal 



Fig. 43. — Pharynx, crop, anterior gastric caeca, and associated organs of 

 Dissosteirn Carolina. 



Ao, aorta; CA, corpus allatum (?) ; Cr, crop; FrGng, frontal ganglion; GC, 

 gastric caecum ; LNv, lateral stomodeal nerve ; OeGiiy, posterior median or 

 oesophageal ganglion ; Phy, pharynx ; PLGng, posterior lateral stomodeal gan- 

 glion ; Pvcnt, proventriculus. 



and the supra-hypopharyngeal walls are directly continued into the 

 anterior and posterior walls of the buccal cavity and pharynx. 



The stomodeum of the grasshopper extends from the mouth upward 

 in the anterior part of the head (fig. 41). then turns posteriorly above 

 the tentorium, and continues rearward through the head and thorax 

 into the base of the abdomen (fig. 43). By differences in its diameter 

 and in the character of its walls, the stomodeum is differentiated into 

 several parts, but only three parts are well defined in the grasshopper ; 

 these are the pharynx, the crop, and the proventriculus. 



The pharynx, or first division of the stomodeum. is a narrow, mus- 

 cular-walled tube bent downward to the mouth between the anterior 

 arms of the tentorium (figs. 41, 43, 44, PJiy). The region of the 

 mouth, including the upper end of the preoral cavity (fig. 41, PrC) 

 and the part of the stomodeum just within the oral aperture, may be 

 distinguished as the buccal covitv because the muscles inserted on it 



