508 Mr. C. L. Withycombe's Notes on 



contents. At the pyloric end of the stomach the alimentary 

 canal is suddenly constricted, and the hind-gut becomes in 

 fact a solid cord of degenerate cells. Thus there is no 

 connection with the anus. At the same point of constriction 

 eight colourless Malpighian tubes are given off radially. 

 Two of these are free distally, but the remaining six once 

 more join the alimentary canal lower down and run in con- 

 tact with it for a short distance. Then there is a swelling, 

 formed by forward growth of epithelial cells over the ends 

 of the Malpighian tubes. Continuous with this swelling is a 

 reservoir, which gradually tapers and is continuous with the 

 rectum. Contrary to common statements on Neuropterous 

 larvae the six attached Malpighian tubes are functional 

 throughout life and secrete a yellowish-brown viscous 

 fluid, which is probably waste, though it serves a useful 

 purpose. It stands to reason that with all the fluid nutri- 

 ment taken during life, some must be excreted, even though 

 that food is so digestible that the entire solid waste can be 

 stored. The attached Malpighian tubes possibly serve as 

 drains to the mid-gut. When the larva wishes to attach 

 itself, as for ecdysis, the anal papilla is furnished with a drop 

 of the viscous adhaesive fluid. The reservoir serves to store 

 the fluid temporarily, and if a larva be suddenly shaken off 

 a leaf, in its endeavours to secure a hold at once, quite a 

 quantity of this excretion may be poured out. In the 

 third instar, the cells in the middle and partly posterior 

 of the Malpighian tubes swell, and the nucleus of each cell 

 in this region becomes ramified as in true silk glands ; in 

 fact, these cells secrete silk instead of the previous gummy 

 fluid. The ramification of the nucleus is not at all well 

 marked in our British forms, and degenerates shortly after 

 spinning has commenced. In Myrmeleonidae, however, it 

 is very distinct and apparently of longer duration. The 

 silk secreted collects in the reservoir and is later spun out 

 through the anus. Coniopterygidae (Plate XLIII, fig. 5) 

 differ in having only six Malpighian tubes, four of which 

 are attached and secrete silk. I have never seen a ramified 

 nucleus here, though curious changes take place. In the 

 Megaloptera, RajDhidiidae, the larva has also six Malpighian 

 tubes, and four of these are looped, but no silk appears to 

 be secreted. 



Salivary glands consist of a pair of simple tubular glands 

 lying mainly within the head, and running one to the base 

 of each maxilla. There appears to be another small gland 



