I am surprised to find that the fossils you collected from the D zone of the Nanushuk group are identical specifically with species in the E zone and represent the same assemblage as in the Dunvegan formation of the western interior of Canada (see Canada Geol. Survey Paper 45-27, 1945). The Dunvegan formation on the basis of its ammonites is of Cenomanian age and probably only upper Cenomanian. The species in common are Arctica? dowlingi (McLearn) and Inoceramus cf. I. mcconnellis Warren. The latter occurs in the E zone in lots 52 ADt 102 and 52 AB1 45. It differs from the holotype cf. I. mcconnelli Warren (1930, Research Council of Alberta Report No. 21, p. 60, pl. 4, figs. 1-3) only by having coarser ribbing, but a specimen figured by McLearn (Canada Geol. Survey 45-27, pl. 3, fig. 2, 1945) suggests that the species may include specimens having appreciably coarser ribbing than the type. The species identified as Arctica? dowlingi (McLearn) was placed by McLearn in Unio (Pleurobema) but appears to be closer to Arctica. A closely similar species listed as “Arctica” n. sp. was found by Cobban and Reeside near the base of the Frontier formation in beds of probable Cenomanian age (see Cobban and Reeside, 1952, A.A.P.G. Bull., vol. 36, p. 1928).

The fossils from the C zone of the Nanushuk group include two species (lot 52 ADt 207) that are different from any species found in zone D. One of the species is a Tancredia similar to Tancredia stelcki McLearn (1954, Canada Geol. Survey Paper 44-17, pl. 10, fig. 5) from the Canadian Goodrich formation of probable late Albian age. The other species is a fine-ribbed Inoceramus comparable with I. tenuis Mantell which in Europe ranges though the late Albian into the lower Cenomanian. I. tenuis occurs in Alaska in the Chitina Valley at the top of the Kennicott formation just above an ammonite assemblage of late Albian age. The presence of this Inoceramus suggests, therefore, that the C zone represents either latest Albian or early Cenomanian or both.