40 JOURNAL OF ENTOMOLOGY AND ZOOLOGY 



into the crop. It seems In this larva to be an organ well adapted 

 to performing two functions, the anterior part serving to triturate 

 the food, while the posterior part acts as a strainer and also brings 

 about a gradual passage of food into the mid-intestine. 



V. Summary 



1. The proventriculus in the Order Trichoptera has been little 

 studied and this organ in the larva of Hydropsyche shows it to be 

 very well developed. 



2. It is unique in the large number of well-developed teeth in 

 the anterior part of the organ, and in the presence of two valves in 

 the posterior region which are continuous with the oesophageal 

 valve. 



3. The oesophageal valve, instead of being a complete tube, is 

 open along its whole extent on one side. 



4. The arrangement of muscle layers in the fore-intestine is the 

 reverse of that typically found in insects, and consists of an inner 

 layer of circular muscles and an outer layer of longitudinal muscles. 



5. The teeth are comparatively solid, lacking the lining of 

 epithelial cells found in forms previously described. 



6. The chitin of the teeth is formed in part by a secretion of 

 epithelium and in part by a transformation of the cytoplasm of these 

 cells. 



7. The anterior part of the organ serves to triturate hard parts 

 of the food, while the posterior part acts as a strainer and also 

 permits a gradual passage of food into the mid-intestine. 



BIBLIOGRAPHY 



Basch,S. 1858 



Untersuchungen iiber das ch3dopoetische und uropoetische System 

 der Blatta orientalis. Sitzungsber. d. math. nat. Kl. d. Acad. Wein., 

 vol. 33. 1858. 

 Bordas,L. 1896 



Appareil digestif des Blattidae. Bull. Mus. hist. nat. Paris, 

 1896. 

 Bordas,L. 1905 



Der Kropf und Kaumagen einiger Vespidae. Zs. wiss. Insek- 

 tenbiol, vol. 1, pp. 325-329, 361-371, 415-418. 1905. 



