JOURNAL OF ENTOMOLOGY AND ZOOLOGY 39 



greatest activity — spring and summer — the large bulk of the food 

 is of animal nature. It is composed, for the most part, of May-fly 

 nymphs (Heptagenia) , Chlronomid and Simulium larvae. The 

 remainder of the year, diatoms and filamentous algae furnish prac- 

 tically all of the food. 



As is known, the Hydropsyche larvae erect catching-nets of silk in 

 front of the larval dwelling tube. The mouths of these nets face 

 upstream, and the current flowing through, leaves entangled in the 

 meshes, animals and plants too large to filter through them. The 

 caddis worm uses its fore legs and mandibles for seizing its victim. 

 Then, instead of chewing the prey, it proceeds to shove it into the 

 mouth with its front legs until it entirely disappears. 



The results of the action of the numerous teeth of the proven- 

 triculus during the contractions of the strong circular muscles are 

 seen when a comparative study of the food-contents of the oesopha- 

 geal region, proventriculus, and mid-intestine are made. The 

 oesophagus often contains unmutilated Chironomid larvae, and but 

 slightly dismembered May-fly nymphs. In the lumen of the proven- 

 triculus, however, and in the grooves between the teeth are found 

 separate mouth parts, tarsal claws, portions of caudal setae, etc. 



The hard parts of the food content are not held back by the 

 proventriculus and vomited through the mouth as described by 

 Ramme (1913) for Dytiscus circumcinctus, but pass through the 

 whole alimentary tract, as has been observed in the Orthoptera. 

 In Corydalis, also, a mandible of an insect has been found in the 

 hind intestine. In examining the fine food broth of the mid-intes- 

 tine many small pieces of chitin are found. 



The interlocking of the numerous, forward-pointing bristles in 

 the posterior region of the proventriculus makes an excellent 

 strainer for holding back particles which have not been sufliciently 

 ground. The two valves act as a stopper and by a regulation of 

 the size of the lumen between them, which is brought about by the 

 action of the circular muscles, a gradual passage of food into the 

 mid-intestine is insured. 



As far as I have been able to observe in Hydropsyche, I find 

 no evidence to support the view that the proventriculus serves as 

 an organ to facilitate the passage of the mid-intestinal secretion 



