19 ZO 



Fig. is.— Tn'coryt/ius sp. Nymph, I. Gill-cover (s:c.) of right side removed, showing gills (g^.): J-g:, filameiitar gill. 



(After Vayssiere.) 



Fig. 16— Li/kamaniis carl'onaruis, g. /./., pro-thoracic lobe. (After H. Woodward.) 



Fig. 17.— Per/a sp. Nymph. ^.<., tracheal gill. (After Vayssiere.) 



Fig. i%.—Euphoberia/erox, Salter, \. Section of a segment, d.s., dorsal shield with spines. (After H. Woodward.) 



Fig. 19 —Polydesmus complanatus. Larva, just hatched, a, antenna ; ^.c, gnathochilarium ; c, cheek ; /,, /., /,, the 



three pairs of legs. (After von Rath.) 

 Y\ii.iQ.—Scutigera.colcoptera. Tracheal mass of a dorsal plate, a, from above ; i^, transverse section. (After HaabC.) 



