BY R. J. TILLYARD. Ill 



Fig.26.— T.S. throu^'h median jrill of AvMroayn'ov cyane (Selys). 0-06mni. 



distad from the breaking-joint; ( x207). 

 Fi.tj.27.— Another T.S. through same gill, but O'lomm. distad from the 



breaking-joint; { x207). 

 (For T.S. of same gill much further distad, see Plate v., tig. .38). 



Plate iv. 

 Fig.28.— T.S. through median gill of Xeo.'^ticta cane.'iefv.^ Tillj'ard. Saccoid 



Type; ( x 130). 

 Fig. 29. — Small portion of cuticle and hj'podermis from same series of 



sections as Fig.28, to sho^' formation of the internal lamina (?/) 



in a larva approaching ecdysis; ( x 490). 

 Fig. 80. — Small portion of alveolar mesh work from same series of sections, 



to show two of the alveolar nuclei in situ; ( x 490). 

 Fig.81.— T.S. through alveolar meshwork of Dr. Ris' larva of Pseudoplx^a 



rariegata (Ramb.), to show tufts of moss-like fibrils in the alveoli. 



The two dark rounded masses are amoebocytes imprisoned in two 



of the alveoli. Photomicrograph from Ris [28]. (Magnification 



not stated, but appears to be about 250). 

 Fig.82. — The two middle alveoli from Fig. 31, much enlarged, to siiow tuft 



and amo^bocyte. From Ris [28]; ( x Leitz Imm. 1/12). 

 Fig. 33. — Another alveolus from same gill, much enlarged, to shoM' tufts. 



From Ris [28]; ( x Leitz Imm. 1/12). 



Plate V. 



(Transverse sections through caiidal gills, taken far from base). 



Fig. 34. — T.S. through median gill of Calopteryx sp. Triquetro-quadrate 



Type; (x 87). 

 Fig, 3."). - T.S. through left lateral gill of same; ( x 87). 

 Fig,36. — T.S. through median gill of Anstrole-ste-s leda (Selys), showing 



central portion or rachis only. Vertical Lamellar Type, Lestid 



form; ( x 207). 

 Fig.37. — T.S. through left lateral gill of same, showing rachis and most of 



the blade; ( x 207). 

 Fig. 38. T.S. through median gill of AvMroagrion cyane (Selys), showing 



rachis and part of the blade. Vertical Lamellar Type, Afjrionid 



form; (x207). 

 Fig. 39. -T.S. through left lateral gill of same, showing rachis only; ( x207). 



Plate vi. 

 (Transverse sections of Horizontal Lamellar Type of Gill). 

 Fig. 40. -T.S. through median gill of AryioleMes icterome/a-<i Selys, close to 

 base; ( x 87). 



