The Otapirian Stage of the Triassic System of New Zealand Part I By J. D. Campbell, Canterbury University College, and I. C. McKellar, New Zealand Geological Survey. [Read before the Southland Branch, June 22, 1955; received by the Editor, July 8, 1955.] Abstract The Otapnran Stage is defined; a description is given of the sequence at the type locality, Otapiri Valley, western Hokoui Hills, Southland, and species described from Otapinan localities are listed. Introduction The type locality of the stratigraphic unit formerly known as the Otapiri Series, now the Otapirian Stage (as defined by Marwick, 1953, p. 18), lies in the Otapiri Valley, western Hokonui Hills, Southland. The section exposed along Otapiri Stream (which includes most of the type section) received detailed treatment by Cox (1878) and McKay (1878), but a re-examination of it is nevertheless timely. First, the exact geographic-and hence stratigraphic-positions of some of McKay's localities are not clear from the descriptions. Secondly, the systematic work of Trechmann and Marwick by no means exhausts the fauna known from other Otapirian localities. Some undescribed forms could be useful for correlation elsewhere if their positions in the type sequence were known. Coombs (1950, p. 439) noted a “large and handsome Lima” from the Otapirian beds in the northern Taringatura Hills. The same form is abundantly preserved in the southern Taringaturas. Undescribed pelecypods dominate the Otapirian fauna in the Kaihiku Stream-Puerua River area. That some of these forms might occur in beds at the type locality is suggested by Hector's (1878, p. x) list of 17 Otapirian species other than brachiopods, of which at least 10 remain un-described. It should be noted that the fauna might have been more fully described had Hector's material been better preserved (Marwick, 1946, p. 49). The field work for this paper was done jointly by the writers, with the willing assistance of Abdullah, a student at the Otago School of Mines. Complete responsibility for the map is accepted by one of us (I. C. McK.) while the definition of the stage and the fossil determinations are entirely the work of the other (J. D. C). Fossil localities are referred to by numbers for fossil record forms based on One Mile Sheet districts, the master file being held at the Invercargill Office of the New Zealand Geological Survey. Historical The first record of the term “Otapiri Series “is found in the catalogue of the Colonial Museum for 1870. Here, Hector (p. 195) listed genera occurring