26 e Can nil inn Arctic Expedition, WIS- IS 



EXPLANATION OF PLATE III. 



Plate 2. Spruce from Coppermine River forest, below Sandstone rapids. 



Fig. 1. Section showing work of Polygraphus rufipennis Ky., beneath the bark. 



Fig. 2. Spruce branch showing tunnels of Carphoborus andersoni Sw. 



Fig. 3. Spruce branch showing tunnels of Xylotrechus undulatus and Neoclytus mwicatulus. 



Fig. 4. Same as figure 3, the reverse side. 



