62 



(1) Somewhat diamond-shaped. 



(2) Setae none on mentum ; about two on each palpus, but 



perhaps of little use. 



(3) Mi'diflii lobe very deeply cleft in the mature naiad, though 



less so in earlier stages. (Archaic.) 



(4) Palpi slender ; three teeth — the end hook and two 



between it and the moveable hook. 



(5) Moveable hook well developed. 



It has been suggested that the cleft may be of use to get rid of rejected 

 remains of food (?). 



iB. Lestinae. T.estea spoma, Hans. (PL VIIL, fig. 6). 



(1) Shape much as in Aririonidae. 



(2) Eaptoiial setae — two on moveable hook, one on lateral 



lobe, a row of a few on mentum. 



(3) Median lobe cleft. 



(4) Palpus with large teeth of various shapes. 



(5) Moveable hook well developed, bearing setae. 



Teeth increase in size as naiad develops. Presence of setae on moveable 

 hook is an important feature. 



7. Agrionidae. Iu-i/thro)iiiiia naias, Hans. (PI. VHI., fig. 7). 



(1) iVfl,s/<- lengthened, contracting basally ; mentum short. 



(2) Raptorial setae — lateral and mental. 



(3) Median lobe prominent, triangular. 



(4) Palpus having end-hook fairly developed. 



(5) Moveable hook moderately developed. 



Homology of the parts of the dragonfly labium. 



