The Permian genus Spiriferella from the Yukon Territory is analyzed by detailed study of internal and external morphology along with stratigraphic occurrence. Among characters of specific importance are the muscle platform,

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bundling of ribs, sinus angle, median fold and micro-ornament. Five species are resognized, Spiriferella saranae, S. rajah var. A, S. rajah var. B, S. keilhavii, S. ordinaria and S. editiareatus, which fall in two slightly overlapping intervals. The lowest of these, of probably Wolfcampian and Leonardian age, represented in the upper third of the Middle Recessive Unit and lower half of the Tahkandit Formation, contains Spiriferella saranae, S. rajah var A, S. ordinaria and S. editiareatus. The upper interval, of probable Upper Leonardian to Guadalupian age, is represented in the upper half of the Tahkandit Formation and contains Spiriferella rajah var B and S. keilhavii.

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