English: Scanning electron microscope (SEM) photomicrographs of some representative conodont elements from the Gasconade, Roubidoux, and Jefferson City formations in southeastern Missouri. Illustrated specimens are reposited in the type collections of the Paleobiology Department, U.S. National Museum (USNM), Washington, D.C. 20560. A_B, Juanognathus? felicitii (Ji and Barnes); posterolateral views of two specimens from sample RC-149 at Roubidoux Creek section, X 85, USNM 498496 and 498497. C, Drepanodus sp., inner lateral view of drepanodontiform element, from sample RC-149, Roubidoux Creek section, X 85, USNM 498498. D_E, Colaptoconus quadraplicatus (Branson and Mehl); posterolateral (D) and lateral (E) views of triplicatiform and quadraplicatiform elements, respectively; D, from sample JF-H, Jacks Fork section, X 110, USNM 498499; E, from sample JC-J, lower part of Jefferson City Dolomite at Jim's Creek section, X 64, USNM 498500. F, cf. Colaptoconus quadraplicatus (Branson and Mehl); shallowly grooved specimen, from sample JF-J at Jacks Fork section, X 90, USNM 498501. G, Ulrichodina deflexa Furnish; posterolateral view of immature(?) specimen from lower part of Jefferson City Dolomite at Jim's Creek section, sample JC-J, X 110, USNM 498502. H, Paroistodus? sp.; inner lateral view of scandodontiform element, same sample and location as G, X 110, USNM 498503. I_L, Histiodella donnae Repetski; posterior views of blade-like elements (I, K, L) and inner lateral view of coniform element (J), from samples JF-H (K) and JF-J (I, K, L) at Jacks Fork section, I and J -X 90, K -X 170, L -X 110, USNM 498504_507. M. Laurentoscandodus? n. sp.; inner posterolateral view of short-based element, from sample JF-J at Jacks Fork section, X 70, USNM 498508. N, Drepanoistodus sp.; inner lateral view of drepanodontiform element, from sample JF-J at Jacks Fork section, X 90, USNM 498509. O, Juanognathus? n. sp.; posterior view of nearly symmetrical element, from sample JF-J at Jacks Fork section, X 90, USNM 498510. P_Q, Striatodontus? prolificus Ji and Barnes; posterolateral views, P from sample JF-J at Jacks Fork section, X 90; Q from upper part of Gasconade Dolomite (sample RC-02) at Roubidoux Creek section, X 95, USNM 498511 and 498512. R_S, Oneotodus aff. O. simplex (Furnish); posterior and lateral views of two specimens from lower part of upper Gasconade Dol. at Phillips Quarry, Bartlett 7-1/2 minute quadrangle, Shannon Co., MO, X 65, USNM 498513 and 498514. T, Chosonodina herfurthi Müller; posterior view of specimen from upper part of middle Gasconade Dol. at Phillips Quarry, X 75, USNM 498515. U, Rossodus manitouensis Repetski and Ethington; inner lateral view of coniform element; same sample as T, X 50, USNM 498516. V, Loxodus bransoni Furnish; inner lateral view; specimen broke during preparation; from upper part of middle Gasconade Dol. at a section near Rolla, MO, X 45, USNM 498517. W, Acanthodus uncinatus Furnish; lateral view of non-serrate suberectiform element, from same sample as T, X 50, USNM 498518. X, Variabiloconus bassleri (Furnish); inner lateral view, X 60, same sample as T, USNM 498519. Y, Oneotodus simplex (Furnish); lateral view, X 75, USNM 498520. Z, Scolopodus sulcatus Furnish; inner lateral view of scandodontiform element, X 75, same sample as T, USNM 498521