1913] Kershaw — The Alimentary Canal of Flata and other Ilomoptera 185 



the midgut is also chitinous though very thin. Both epithelia 

 are very similar and secrete a more or less chitinous material 

 from the free ends of the cells, though the somewhat chitinous 

 intima is modified from the highly chitinous secretion of the cuticle. 

 Of the two mesodermic tissues the muscular layer invests the 

 inner wall of the body-cavity and also what is really (if the whole 

 gut is of ectodermic origin) the inner wall of the alimentary canal; 

 the intima of the lumen being its outer or external wall; it also 

 invests the appendages of the gut. The peritoneal layer forms 

 in Siphanta an apparently complete investiture of the alimentary 

 canal, though it is in some parts exceedingly thin and barely 

 visible. In the embryo the peritoneal layer seems to originate 

 in close connection with the pericardial and neural septa. 



If the midgut is really of ectodermic origin, then that part of 

 the secretion which eventually seems to produce the peritrophic 

 membranes is probably a modification of the secretion which forms 

 the chitinous cuticle. The membranes resist for some time the 

 action of potash: however, the secretion which produces chitin 

 is easily soluble in potash if it is acted upon soon after being 

 secreted and before much exposure to the external air. The 

 secretions of certain colleterial glands also are very soluble in 

 potash when freshly secreted, but soon become almost insoluble, 

 apparently from the action of the external air. 



In the Cixiid genus Oliarus, at least in the Hawaiian species 

 (fig. 6), the anterior part of the reservoir extends to the head but 

 does not enter it: makes a sharp bend and returns through the 

 thorax to near the abdomen, lying close alongside the posterior 

 part. In the younger nymphal instars the reservoir is not so 

 long, and has no bend and return portion, but this develops before 

 the final moult to adult. The malpighian tubes are forked distally 

 for a great length, the forked portion being lobulate, the rest 

 smooth and of smaller diameter. They are generally of a pale 

 brown . 



In Dictyophorodelphax mirabilis Swezey, an endemic Hawaiian 

 Delphacid (fig. 7), the reservoir enters the headcapsule and con- 

 tinues to the tip of the greatly produced epicranium. The mal- 

 pighian tubes are forked distally for a moderate length, the forked 

 part being lobulate, the rest smooth. They are of a pale brown. 



In Perkinsiella saccharicida Kirk., a Delphacid (fig. 8), the 



