PLATE 18. Tesselacauda kriegerae n in Revision of the Early Ordovician (late Tremadocian; Stairsian) cheirurid trilobite Tesselacauda Ross, with species from the Great Basin, western USA

PLATE 18. Tesselacauda kriegerae n. sp., from Section HC6 122.5–124.0 m, Garden City Formation (upper Tremadocian; Stairsian; Bearriverops alsacharovi Zone), west side of Hillyard Canyon, Bear River Range, Franklin County, southeastern Idaho, USA. 1. Left librigena, SUI 147634, external view, x20 (HC6 124.0 m). 2. Right librigena, SUI 147635, external view, x20 (HC6 124.0 m). 3, 7, 9. Hypostome, SUI 147636, ventral, left lateral, and posterior views, x12 (HC6 124.0 m). 4, 5, 8, 10. Hypostome, SUI 147637, ventral, left lateral, posterior, and anterior views, x15 (HC6 124.0 m). 6. Right librigena, SUI 147638, external view, x15 (HC6 124.0 m). 11, 12, 14, 16. Hypostome, SUI 147639, posterior, ventral, right lateral, and anterior views, x12 (HC6 124.0 m). 13, 15, 17, 20, 24. Thoracic segment, SUI 147640, dorsal, ventral, anterior, posterior, and right lateral views, x15 (HC6 124.0 m). 18, 19, 21, 22. Hypostome, SUI 147641, ventral, anterior, right lateral, and posterior views, x25 (HC6 124.0 m). 23, 26, 27. Pygidium, SUI 147642, dorsal, posterior, and right lateral views, x15 (HC6 122.5 m). 25, 28, 29. Pygidium, SUI 147643, left lateral, dorsal, and posterior views, x20 (HC6 122.5 m).