The large ornamented Frondicularians have all gone, there are no Planularias, and the Palmulas are of altogether different and Tertiary types. The Lower Eocene Midway fauna is as closely related to our Upper Piripauan as to any of our Eocene faunas, being in many features “midway” between the two. The most significant New Zealand micro-fossils from this aspect are Assilina, Discocyclina and Asterocyclina (Chapman, 1932, p. 483); the last has been quoted as restricted to Upper Eocene, but is given by Galloway and by Vaughan as also Middle Eocene; it occurs in the Dutch East Indies and Australia (Chapman and Crespin, 1935, p. 60) as characteristic of “stage b” (of van der Vlerk and Umbgrove, 1927) placed as Middle—Upper Eocene. In a recent tabulation by Senn (1935, Pl. 9) Assilina is given a range of only Lower—Middle Eocene (just into Upper Eocene in Egypt), while Asterocyclina is confined to Upper Eocene in America and Venezuela, but also reaches Middle Eocene in Morocco and Europe. This would seem definite evidence that the Upper Bortonian at least is Middle Eocene.

Of other restricted genera Hantkenina is the most impressive. H. australis Finlay (1939B, p. 538), a species close to the genotype, has been found at several localities in the Upper Bortonian; since it was recorded, specimens have been found also in the Kaiatan (Kaiata mudstone of Westland and Maheno chalky clays of North Otago), here referred to the Lower Oligocene. This is the same range as that of the genotype in America; while the nearest relatives to the New Zealand shell, alabamensis Cush. and brevispina Cush., have also been recorded from the Upper Eocene and Lower Oligocene of French Morocco (Rey, 1938, p. 331). Cushman (1939, p. 38) has reported that no authentic species of Elphidium is known below Middle Eocene; the genus is absent from our Cretaceous and Lowest Bortonian (which may be Lower Eocene), but two typical species occur in the Lower and Upper Bortonian respectively, already referred to Mid-Eocene by Finlay. There are also some striking affinities with the Eocene of Mexico, particularly the Lower Eocene Aragon formation. Nuttallides Finlay of the trümpyi type is not uncommon throughout our Bortonian (but absent from the Tahuian, Uppermost Eocene) and extends down to the Upper Piripauan; in Mexico it extends similarly throughout the Eocene, while in French Morocco it is dominant in the Middle Eocene, but also extends halfway through the Upper (Ostrowsky, 1938, table opposite p. 352). Globorotalia crater Finlay, so characteristic of our Lower Bortonian, is close to the Mexican crassata Cush. and aragonensis Nuttall (from the Aragon formation, classed as upper part of Lower Eocene), and less like the Danian velascoensis Cushman, while the Bortonian genus Aragonia Finlay (of Bolivinoides affinity) has close Mexican allies in the Velasco and esecially Aragon, and is unknown above the Eocene. Marginulinopsis asperuliformis Nuttall, an index species of the Aragon (see Nuttall, 1930, pp. 277, 282) is extremely close to the Lowest Bortonian M. waiparaensis Finlay, while the Middle and Upper Eocene Californian M. nudicostata (C. and H.) is just as close to our Lower Bortonian marshalli Finlay. The French Cretaceous genus Citharinella Marie