Number and arrangement of 



gills of L. centra lis 





Segment 



Dorsal 



Pleural 



Ventral 



2 



3 

 3 



2 



2 



3-2 

 3 



3 



3 

 3 



2 



1 



3-2 

 3 



4 



3-2 

 2 







2 

 2 



5 



2 

 2-1 







2-1 

 2 



6 



1 

 2-1 







2-1 

 2-1 



7 



1 (0) 







1(0) 

 1(0) 



Case made of fine sand grains, smooth, slightly curved, tapering 

 posteriorly (Figure 383); anterior opening truncate, posterior opening 

 closed by a membrane with a large, round hole. 



(219) 



381 



38^ 



FIGURES 381-384. Limnophilus ce nt ra li s Curt.: 



381 — right trochanter and femur of foreleg (A),midleg (B), 

 and hind leg (C), posterior; 382 — tergite of segment 9; 

 383 — larva in case; 384 — pupa: dorsal process of abdominal 

 segment 1 (A), anal rods (B),per'.s sheath and ventral appen- 

 dages (C) (383 - after Hickin; 384 - after Siltala). 



273 



