18 



Explanation of Plate I. 



Fig. 1. Full-grown hiiva. 3^. 



Fig. 2. Pupa. \^. 



Fig. 3. Wingless adult female. ^. 



Fig. 4. Winged adult female. ^■^-. 



Fig. 5. Head of Poa pratensis normally developed. J. 



Fig. G. Head of Poa pratensis arrested in its growth by the attack of Anai)holhrvps 



striata (Osb.), also showing the shrivelled condition of tlie stem just 



above the upper node. J. 



