Appendix. Whangarei Heads Xenoliths and Their Comparison with Rocks of Southern New Zealand. By F. J. Turner, Otago University, Dunedin. Origin of the Rocks. Although the classification of the metamorphic xenoliths from Whangarei Heads set out in the paper above includes suggestions as to the derivation of the various types, the well-known similarity of end-products of high-grade metamorphism of rocks so diverse as basic igneous rocks and tuffs, impure calcareous sediments and greywackes makes it impossible to be certain of the origin of rocks in Class III of that classification. Similarly individual rocks of Class II may well be derivatives of sediments, although the general small content of quartz and lack of mica and garnet are somewhat against this possibility. All appear to be products of metamorphism of the highest grade, for minerals such as diopside, pleonaste, and basic plagioclase indicate high temperature. The almost universal schistose structure indicates, however, that shearing stress was in operation. There are thus two alternatives:— 1. Contact metamorphism with accompanying shearing stress. 2. Regional metamorphism of highest grade. Even in this case, however, some contact action is necessary to account for scapolite in one rock and pleonaste in another. The preferable alternative is that which regards the series of rocks as essentially the product of contact metamorphism. Comparison with Rocks of Southern New Zealand. There is seldom any approach to identity of individual rocks between the Whangarei Heads rocks and those of southern New Zealand. Considerable similarity exists, however, without actual identity in the following examples in which the Whangarei rocks are mentioned first:— 1. The noritic hornblende-gabbros parallel those of the Bluff, Orepuki and other Southland intrusions (cf. Service, 1937). 2. Quartz-biotite-norite: the occurrence of this type recalls the biotite-norites of Fiordland, although the resemblance is not close. 3. Hornblende-plagioclase-gneisses are more or less matched by somewhat similar rocks at Manapouri; these latter, however, have more sodic plagioclase and usually biotite and epidote. 4. The hornblende-diopside-plagioclase-gneisses recall similar rocks with green diopside near Anita Bay, Milford Sound, which were shown the writer by Dr. P. Marshall. 5. The hornblende-epidote-schist compares closely with some Manapouri gneisses.