The coxa is massive and articulated with the pleural sclerite. It contains 

 a very large muscle and the base of the coxa is therefore always markedly 

 thickened. The dorsal surface of the basal part of the coxal sclerite is 

 concave. It is deeply notched in the distal part, and there is a large 

 membranous area; this notch encloses the dorsal margin of the femur when 



23 the femur is moved laterally. The coxal sclerite is very strong because of 

 the thickening of its basal margin which forms a massive dark rim, 

 connected at the inside by a fold of the sclerite. The basal margin of the 

 coxa has an articular process dorsally, which enters into the cavity on the 

 inner side of the episternum, to which it is attached by skeletal fibers; 



the apex of the articular process of the basicoxite of the foreleg is wedged 

 into the corner formed by the trochantin and episternum. This articulation 

 ensures freedom of movement of the leg, especially for the complicated 

 movements during the building of the case. 



The coxa articulates with the trochanter at two points at the sides of 

 the ventrodistal margin of the coxa. The coxa bears 7 primary setae: 

 3 dorsal setae (2 anterior and one posterior to the groove), 2 anterior 

 surface setae and 2 ventrodistal setae; one of the 2 anterodorsal setae is 

 situated basally (basodorsal seta) and the second one is situated near the 

 apex of the dorsodistal depression; the dorsal setae may be very long; 



24 the setae are usually short, slightly marked, rarely long; they are divided 

 at the end in some groups; the ventrodistal setae are either short or long; 

 one seta is longer than the other. 



The trochanter is situated between coxa and femur; it articulates with 

 the coxa at one end and with the femur at the other; the dorsal short side 

 of the trochanter bears in some cases only a narrow transverse hard 

 sclerotized band or is not sclerotized at all, so that the sclerite is dorsally 

 membranous. The trochanter is divided into a short basal part and a 

 larger distal part by a suture near its basal margin; this suture is 

 incomplete and interrupted ventrally. The basal margin of the sclerite 

 bears two articular processes for its connection with the coxa; the 

 trochanter is contiguous with the femur at its distal margin; in some forms 

 (species of Rhyacophila) trochanter and femur are only partially 

 contiguous anteriorly, and a small membranous part is present; posteriorly, 

 the distal margin of the trochanter is displaced to the basal margin of the 

 femur and is tightly connected with it, so that femur and trochanter act 

 functionally as one segment. The above form of the trochanter is mainly 

 characteristic for the forelegs; it is also characteristic for the middle and 

 hind legs in many groups. In some families (Limnophilidae, Leptoceridae) 

 the trochanter is oblong, curved, with a distinct dorsal surface or forms 

 a straight rodlike structure. The trochanter bears 7 primary setae: 

 2 surface and 5 ventral setae; both the surface setae (anterior and posterior 

 seta) are situated apically or subapically; of the 5 ventral setae (distal 

 and subdistal) 2 are situated posteriorly, and 3 anteriorly (one long seta is 

 situated basoventrally near the suture and 2 usually spinelike setae are 

 situated apically and subapically); several ventral setae of the distal section 

 of the trochanter of the middle and hind legs are very long. 



The dorsal surface of the femur is longer than its ventral surface; the 

 femur has a deep ventrodistal depression in which the tibia is situated 

 when the leg is folded; the femur is ventrally membranous in some groups 



20 



