PLATE XXIII 
LEAVES OF THE WYCH ELM (UlmUS glabra) WITH GALLS CAUSED BY 
THE PRESENCE OF THE LARVAE OF THE ('.ALL-GNAT OligOtrofllUS 
Leevtei. a, young leaves much distorted and swollen ; 
B, UPPER SURFACE SHEWING EXIT HOLES; C, LOWER SURFACE WITH 
GALLS IN A LATERAL POSITION ON THE MID-RIB 
