up into the Campanian in England. The age is thus probably upper Santonian to lower Campanian. The single ammonite from the Teratan—Gaudryceras sp.—is related to forms that range from Turonian to Campanian (Wright, 1957: 806). The Mangaotanean cannot be closely correlated. The key species, I. bicorrugatus, is not close to any known overseas form but has a general resemblance in adult ornament and in sudden change of form during growth to some members of the large species-complex described under I. inconstans Woods (1912) that range from Coniacian to middle Santonian. The juvenile part of the shell is similar to a British Museum specimen (BM L87635) identified as I. inconstans Woods from the lower Coniacian of England. The underlying Arowhanan stage being post-Turonian probably represents part of the Coniacian and the most probable age for the Mangaotanean is upper Coniacian to lower Santonian. No diagnostic ammonites are known from this stage. The Arowhanan is without any good overseas fossil correlatives, and its age is inferred as lower Coniacian from its stratigraphic position. The writer's previous correlation of I. rangatira (I. sp. R of Wellman, 1956) with I. undulato-plicatus Roemer of the lower Santonian was based on illustrations. Comparison of actual specimens has made this correlation unlikely. A possible correlation on description and illustration only is with I. guerichi Heinz (1928) from the top of the lower Emscher (mid-Coniacian) of Germany. No ammonites are known from the Arowhanan. The Ngaterian is fairly certainly middle to upper Turonian in age, the three key Inoceramus species that occur together being members of the I. lamarcki Parkinson species complex that is known in beds of this age at several places overseas. I. fyfei has the characteristic irregular growth lamella of I. lamarcki shown by Seitz as being mid-Turonian and by Woods (1912) as ranging from Turonian to Coniacian. I. tawhanus, considered a variety of I. concentricus by Woods in 1917, appears to be closer to I. lamarcki var. apicalis (Woods, 1912) which ranges through Fig. 12.—Sketch cross-section through the Mangaotane Valley section. Stage symbols as on map. Length of section about 8,000ft. Horizontal and vertical scales are the same. the Turonian of England, to I. coulthardi and I. selwyni of the upper Turonian of Canada (McLearn, 1926), and to I. concentricus costatus N. & M. and I. teshioensis N. & M. of the Turonian of Japan (Nagao and Matumotu, 1939). I. hakarius is similar to specimens of I. lamarcki from the middle Turonian of England (Woods, 1912) and to I. corpulentis McLearn, 1956 from the upper Turonian of Canada. A definite age is given by the ammonite Otoscaphites awanuiensis Wright found with I. tawhanus in a boulder at “Port” Awanui. According to Wright (1957) the age is “undoubtedly Upper Turonian”. An anomalous Cenomanian or upper Albian age is indicated by Mariella aff. cenomanensis found in dark mudstone near Matawai 200ft below Inoceramus fyfei and I. hakarius.