NATURAL HISTORY, TORONTO REGION 
Euura serissimae, Rohwer. Host Salix serissima, 
Fernald. Consists of the enlarged petiole of the 
leaf. The leaves infested are borne on the branch- _ 
lets from which the pistillate catkins spring. 
Pontania pisum, Walsh, Host Salix discolor, 
Muhl. An almost spherical, pea-like gall, with a 
small point of attachment to the leaf of the host. 
Pontania pomum, Walsh. Host Salix cordata, 
Muhl. A large, globular gall originating from the 
leaf of the host. It is greenish-yellow in colour, 
usually with a rosy colour on one side. 
Pontania crassicornis, Rohwer. Host Salix hu- 
milis, Marsh. Resembles the former species in shape, 
but is considerably smaller. It is densely pubescent, 
and several are crowded together on one leaf. 
Pontania desmodioides, Walsh. Host Salix hu- 
milis, Marsh. A smooth, flattish gall with a semi- 
circular outline originating from the mesophyll of 
the leaf. 
Pontania hyalina, Norton. Host Salix alba, L. 
Many galls are produced on a leaf arranged in two 
almost parallel rows, one on each side of the midrib. 
Pontania lucidae, Rohwer. Host Salix lucida, 
Muhl. Produced as an enlargement of the petiole 
or midrib of the leaf. A common gall in High Park. 
Order Hymenoptera. Family Cynipidae. 
Our native oaks furnish the hosts for a large num- 
ber of species in this family, and as a consequence 
they are well represented in our parks. 
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