GEOLOGICAL SURVEY, CANADA PAPER 47-24 NATHORSTITES FAUNA ‘DARK SILTSTONES’ Figures 1, 2, 3. Nitanoceras selwyni McLeam. Holotype, 9047. Figures 4, 5. Same species. Plesiotype, 9526. Figure 6. Nitanoceras leve n. sp. Holotype, 9544. Figure 7. Isculites schooleri var. parvus McLearn. Holotype, 8793. Figures 8, 9. Same variety. Plesiotype, 9527. Figure 10. Isculites schooleri McLeamn. Plesiotype, 9528. Figures 11, 12. Same species. Holotype, 9046. Figures 13, 14. Sagenites gethingi McLearn. Plesiotype, 9529. Figures 15, 16. Same species. Holotype, 8806. PLATE III