adopted such a polemical approach to the problem of Mesozoic faunal realms, for their understanding will benefit from all types of data, including the isotope temperature studies for which he has been responsible. It is too early to be dogmatic and I must apologize if my paper (Stevens, 1963) seemed so. Space limitation prevented full treatment of belemnite faunal realms in my paper, but greater detail is provided in Stevens, 1965, pp. 168-189. As indicated in my paper (1963), the concept of Mesozoic faunal realms or provinces, similar to those of the present-day oceans, but on a broader scale, is not new (Arkell, 1956; Donovan, 1957, pp. 147-8, 155-7) and, furthermore, is not based on belemnite studies alone. Uhlig (1911) and Arkell (1956) recognized a number of Jurassic faunal realms, the majority closely comparable to those distinguishable from belemnite distribution. The differences can perhaps be accounted for by differences in inferred habitats of belemnites (dominantly shelf inhabitants, neritic) and ammonites (free swimming, nektonic). The faunal realms proposed by Uhlig and Arkell were both based on palaeobiogeographic observations built up over a lifetime of experience in palaeontology and stratigraphy. The Boreal realm recognized in belemnites (which Bowen questions before the later Cretaceous) is essentially that recognized by Uhlig, Arkell, and other workers (e

<' I (0 18 ) and <' I (C13) results and isotopic temperatures are presented for transverse sections of New Zealand belemnites (Belemnopsis, Hibolithes, Dimitobelus) obtained from Jurassic strata correlated with Bajocian-Bathovian, Callovian, Kimmeridgian and Lower Tithonian, and Cretaceous strata correlated with Albian-Maastrichtian. Growth layer analyses also were carried out on 15 Jurassic and Cretaceous belemnites.Many of the belemnite specimens were found to be chemically altered to varying degrees, but growth analyses showed that the high isotopic temperatures which alter· ation is expected to produce were confined to two areas: surrounding the apical line and adjacent to the periphery of the specimen. Between these two areas there are generally plausible isotopic temperatures, and there is no reason to suspect that the temperature record has not been preserved there in its original form. Three or four major growth stages may be recognised in New Zealand belemnite guards and growth layer analyses suggest that these are annual; if this is so then in this respect the belemnites match the modern squids in having a three· or four.year life cycle. Variations in isotopic temperature of the be1mnites are comparable with those experienced seasonally by modern squids. Isotopic temperatures for the Jurassic and Cretaceous of New Zealand can be compared with sea water surface temperatures around the present day New Zealand coasts (36 0 _46 0 S. Lat.)' and inferred temperatures, based on these comparisons, are as follows: Upper Jurassic -temperatures slightly cooler than those of the present day; Albian and Cenomanian -temperatures slightly warmer; Turonian-?Coniacian -temperatures markedly warmer; Santonian-Maastrichtian -tem· peratures slightly warmer in the Santonian, but more so in the Campanian and Upper Maastrichtian. The New Zealand oxygen isotope results indicate a probable mid· latitude position, in the warm·temperate climatic zone, for New Zealand in the Jurassic and Cretaceous. New Zealand oxygen isotope results are compared with those obtained from overseas.

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