12 the caddis fly larva and pupa, according to the principles of insect 



morphology established by Snodgrass (1935:1-279). A short survey of the 

 external morphology of the larva and pupa of caddis flies was given in the 

 book of Bertrand on aquatic insects (1954:16-42). Details of the 

 morphology of some species and a few attempts of comparative 

 descriptions of some structures are contained in the bibliography on 

 pp. 174-180. 



;n) 



FIGURE 2. Eruciform larva of Limnophilus flavicornis (A) and its case (B); 

 suberuciform larva of Phryganea sp. (C) (after Hickin) 



Cuticular appendages. The integument, both its sclerotized and 

 its membranous parts, bear appendages of two types, spines and setae 

 (Siltala, 1907:356-365; Nielsen, 1942:263-267). Both types contain 

 characteristic and well- differentiated elements, which differ morphologically 

 and functionally;* spines are strongly sclerotized and have mainly a 

 protective function (rarely filtering or cleaning); the setae are sense organs 

 situated in depressions of the skin (alveoli) connected with a nerve cell at 



* Drawings of spines and setae are given in the systematic part. 



