Figure 8; Idanthyrsus sp. A) Worm inside its tube, B) entire body, C) operculum, D) abdominal uncinus, E) nuchal hook, F) outer opercular paleae, G) radiolar tip of outer opercular palea, H) inner opercular palea. Scale bars: A, C) 2 mm, B) 3 mm, D, G–H) 1000x magnification, E–F) 400x magnification.
Figure 7; Idanthyrsus mexicanus Kirtley, 1994. A) Entire body, dorso-lateral view, B) operculum, dorsal view, C) nuchal hook, D) abdominal uncini, lateral view, E) base of outer opercular palea, F) mid-region of a outer opercular paleae, G) near distal end of outer opercular palea, H–J) inner opercular paleae. Scale bars: A) 3 mm, B) 1.5 mm, C, J) 400x magnification, D–I) 1000x magnification.