Explanation of Plate 7. 



Portion from the edge of the pygidium of different species. 



Fig. i. Chionaspis salicis. 



Fig. 2. Chionaspis herbae. 



Fig. 3. Chionaspis salicis-nigrae. 



Fig. 4. Chionaspis pinifoliae heterophyllae. 



Fig. 5. Chionaspis platani. 



Fig. 6. Second lobe of Chionaspis platani showing variation. 



Fig. 7. Chionaspis ivistariae. 



Fig. 8. Chionaspis pinifoliae. 



Fig. 9. Chionaspis lintneri. 



