IN view of the deplorable effect of repeated defoliation of oaks by the larvae of Tortrix viridana, as noted by Mr. E. W. Swanton in NATURE for August 19, p. 250, it may be useful to remind planters that there are two distinct races of British oak (Quercus robur, Linn.), to which some botanists have assigned specific rank as Q. pedunculata, Ehrh., and Q. sessiliflora, Salisb. The latter, known in the vernacular as the durmast oak, prevails as an indigenous growth in the western and north-western parts of Great Britain, throughout the English Lake District, and in Ireland. In eastern England and Scotland and in midland and southern England the pedunculate oak predominates, but not exclusively, for I have found that the old trees in Merevale Park, Warwickshire, survivors of the ancient Forest of Arden, are durmast, while such oaks as have been planted there are pedunculate.