284 Annals Entomological Society of America [Vol. Ill, 



slight mid-dorsal and ventral protrusions of the epithelium in 

 the ijharynx. persist in the anterior part of the esophagus, 

 forming a slight dorsal and a ventral longitudinal ridge. In the 

 median portion of the esojjhagus these ridges almost disappear 

 while in the caudal region there are two dorsal and two ventral 

 ridges (Fig. 11, ep.) These dorsal and ventral ridges are simply 

 thickenings of the cells opposite the nuclei while the lateral ones 

 are formed by an elevation of the cells from the muscular coat 

 and a protrusion of them half way in to the center of the lumen. 

 The chitinous intima of the esophagus is well developed al- 

 though much less strongly than in the pharynx. It becomes 

 much folded and is usually severed from the epithelium by fix- 

 ation. On the inner surface of the infolded intima of the esoph- 

 ageal valve, there are to be seen, with high magnification, a 

 number of strong spine-like setae, 'but these are absent in the 

 anterior portion of the esophagus (Fig. 17). They are so di- 

 rected as to resist the passage of food from the mid-intestine 

 back into the esophagus. 



The salivary glands are quite prominent, each about the 

 size of one of the lobes of the brain (Fig. 12). They are strongly 

 reniform so that their free ends lie almost directly above their 

 j^roximal ends. When the glands are not secreting their lumina 

 may be very large, but during active secretion they are nearly 

 obliterated. The cells are very large and protrude into the 

 lumen so that in sections there are deep grooves between them. 

 They have a coarse granular and vacuolate appearance, and are 

 usually set off by distinct walls, except during active secretion 

 when these may become obliterated. The nucleus is very large 

 and centrally located, with deeply staining chromatin material 

 and a very large nucleolus. The chitinous intima is quite 

 thick but obscured by the granular nature of the underlying 

 cells and the secretions in the lumen. The limiting basement 

 membrane is very delicate, but stands out distinctly. 



From the ventral anterior end of the glands, ducts pass for- 

 ward and downward to a point beneath the sub-esophageal 

 ganglia where the two join to form the main salivary duct. 

 This main duct passes forward to the mouth where it opens on 

 the surface of the labium between it and the hypo|)harynx. 

 The intima of this duct is quite delicate posteriorly while the 

 epithelium is more ])rominent, but near its anterior end both the 

 intima and epithelium are prominent. Just before the duct 



