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Annals Entomological Society of America  [Vol. VII, 
EXPLANATION OF PLATES. 
PiatTeE I. 
Oak Hedgehog Gall attached to the midrib of a White Oak leaf. 
Longitudinal section through a Gall. A. Central cavities; B. Lateral 
Cavities. 
Agamic form of D. erinacei ovipositing on the bud of White Oak. 
Female, sexual form of D. erinacei. 
Pupa of agamic form of D. erinacei. 
PLATE II. 
Bud scale with eggs of agamic form attached. 
Bud scale with enlarged gall, egg-shell still attached. 
Longitudinal section through Oak Hedgehog Gall showing Peripheral 
Cavity. 
Bud scale on which young gall is forming with empty egg-shell attached. 
Terminal Galls. 
Oblique section through Oak Hedgehog Gall showing where S. erinacei 
has mined from A - B. 
Longitudinal section through Oak Hedgehog Gall showing where S. 
erinacei has mined from A - B, and is breaking down the wall at C. 
PLaTeE III. 
Mandible of Agamic form of D. erinacei. 
Maxilla of Agamic form of D. erinacei. A. Cardo; B. Stipes; C. Palpus; 
D. Galea. 
Labium of Agamic form of D. erinacei. A. Palpus; B. Glossa; C. Para- 
glossa. 
Antenna of Agamic form of D. erinacei. 
Two distal segments of antenna showing sensory pits. 
Aborted wings of agamic form of D. erinacei. 
Larva of agamic form of D. erinacei. 
Egg of agamic form of D. erinacei. 
Mandible of sexual form of D. erinacei. 
Maxilla of sexual form of D. erinacei. A. Cardo; B. Stipes; C. Palpus; 
D. Galea. 
Labium of sexual form of D. erinacei. A. Palpus; B. Glossa; C. Para- 
glossa. 
Wings of sexual form of D. erinacei. 
Egg of sexual form of D. erinace}. 
Scutellum of sexual form of D. erinacei. 
Larva of sexual form of D. erinacei. 
Antenna of sexual form of D. erinacei. 
Distal segments of antenna showing sensory pits. 
PLATE IV. 
Larva of internal parasite from agamic form of D. erinacei. 
Egg of Ormyrus ventricosus. 
Egg of Decatoma flava containing embryo. 
Mandible of Eurytoma larva. 
Larva of Decatoma flava. 
Larva of Eurytoma sp. 
Diagram showing location of setz on segments of larva of S. erinacei 
(spring brood). 
Eurytoma egg with larva emerging. 
Larva of S. erinacei (summer brood). 
Egg of S. erinacei (summer brood). 
Larva of S. erinacei (spring brood). 
Egg of S. erinacei (spring brood). 
