170 throughout life. The case-bearing habit and feeding on algae are connected 

 with a nonactive life on stones among algae; they have a marked effect on 

 the structure of the body of these ancient case bearers,, making them slightly 

 Similar to the larvae of Rhyacophilidae; however, a number of morphological 

 details and the close resemblance of the pupal case and cocoon (which is a 

 sort of reduced replica of the case and cocoon of the pupa of Rhyacophilidae) 

 prove the close relationships between these families. 



The membranization of the mobile larvae of Rhyacophilidae, which do 

 not build a portable case, is developed almost as completely as in the higher 

 Palaeochaetoidea, affecting the dorsum of all abdominal segments except 

 segment 9 and the meso- and metanotum, which bear small sclerites in 

 some genera of Glossosomatidae. 



The development in line 4, which depends on the method of feeding, the 

 time at which building begins and the form of the case, is expressed in the 

 differentiation of branches 4' and 4". In branch 4' developed algophages 

 living without a case in the early stages of development, and building a 

 portable sacciform case at the beginning of the 5th stage; this case is 

 without a lining or has a lining of thin, minute particles which are later used 

 to build the pupal case. Branch 4" developed into detritophages with a 

 tubular portable case with a rich, often bulky, outer layer; this case is 

 built beginning from the lst-larval stage. Branch 4' developed in the recent 

 fauna into the family Hydroptilidae. Branch 4" is considered the ancestor 

 of the whole suborder Integripalpia; this is thus a very recent, highly 

 progressive, and differentiated branch of Trichoptera. 



Line 4' remained conservative; recent species of Hydroptilidae retained 

 a number of very primitive characters of the assumed ancestors of the 

 order; such characters are the small size, the complete dorsal sclero- 

 tization of the thorax (in some genera, also of the abdominal segments), and 

 the predominance of the primary chaetotaxy. 



The pupal case of Hydroptilidae is transformed from the larval case; the 

 insect also builds a pupal cocoon; however, it is not well defined and is not 

 separated from the inner lining of the pupal case. 



In the recent Hydroptilidae, the specialization developed during evolution 

 along line 4' is expressed in the highly differentiated primary chaetotaxy; 

 for example, seta 8 of the claw of the anal leg of Ithytrichia lamel- 

 la r i s has a very unusual spatulate form; the distal dorsal setae of the 

 anal leg of Agraylea multipunctata are unusually long in the 

 4th stage. 



The larvae of most species (including species of Hydroptila) keep 

 a close connection with flowing water; however, some genera, e. g., 

 Agraylea, Oxyethira and Orthotrichia, which feed on filamentous 

 algae, widely inhabit stagnant water; life in such a habitat is observed much 

 more rarely among the other Annulipalpia, i. e., only in the Polycentro- 

 podidae. 



Branch 4" consists of tube-bearing detritophages; this is an ancestral 

 branch which, during its progressive evolution, developed into the 19 families 

 of recent Integripalpia. The high rate of evolution of Integripalpia 

 (branch 4") connected with the complex morphological specialization and with 

 the extension of the ecological range of the group was ensured by the 

 available nutritive food in the form of detritus with its rich fauna of fungi 



171 and bacteria and which is abundant throughout the year in the most diverse 

 habitats of Trichoptera and also by the high development of their building art. 



160 



