11 f 14 



Fig. %—Chloeon dimidiatum. Thorax and anterior segments, f.ii.'., forewing ; h.n<., hindwing ; tr.g., tracheal gills ; 



t.t., tracheal longitudinal trunks. (After Von Graber.) 

 Fig. lo.—Chloeon dipterum. Nymph, \ ; wing-sheath of left side and gills of right side removed, iv.s., wing-sheath ; 



tr.g., tracheal gills. (After Vayssiere.) 



Fig. ii.~Oligoneuria garuinnka. Nymph, f. tr.g., dorsal tracheal gills. (After Vayssiere.) 



Fig. xi.-Sialis lutraria. a, larva ; d, tracheal gill ; ig., base of gill ; i.i., tracheal trunk with which gill is connected ; 



/.a., trachea given off to alimentary canal. (After Dufour.) 



IG. i3.~Sisyrajuscata. a, larva, ventral aspect ; ^, abdominal appendage (gill) ; s.s., sucking spears ; ir.g., tracheal 



giU. (After Westwood.) 

 G- H.—Tnart/irus iccki. Section through second thoracic segment, ^.r, e.xopodite; c«, endopodite. (After Beccher.) 



