=24.= CALHOUN SHALES. This formation is fifty to sixty-five feet in thickness. The lower part is a layer of soft argillaceous sandstone from twelve to twenty feet thick. The upper portion of the formation is a bluish shale, arenaceous below, clayey above, and of comparatively fine texture. No fossils have been collected from this formation, except a few fragments of _Calamites_ and _Cordaites_ in a soft sandstone immediately beneath the Topeka limestone, in the eastern part of that city. The type exposure is at Calhoun’s Bluffs, three miles northeast of Topeka. =25.= HARTFORD (TOPEKA) LIMESTONE. (Adams’s MSS., by permission of U. S. Geological Survey.) The following section of the rocks is about as given by Doctor Bennett when he first described them: ft. in. _g._ Limestone weathering buff 2 0 _f._ Drab shales 3 0 _e._ Limestone weathering buff 1 6 _d._ Buff calcareous shales with abundant fossils 2 0 _c._ Blue to brown limestone, always weathering to a brown 5 8 buff, cherty near the top, fossiliferous _b._ Blue shales 1 6 _a._ Blue limestone, weathering dark buff 6 0 --- --- Total thickness of formation 21 8 Most of the fossils enumerated below were taken from layers _c_ and _d_, though the entire set is more or less fossiliferous, with about the same species running through them. _Fusulina secalica_ (Say). _Amblysiphonella prosseri_ Clarke. _Lophophyllum profundum_ (Milne-Edwards and Haime) Foerste. _Crinoid_ stems and plates, referred by Bennett to _Zeacrinus mucrospinus_ and _Z. acanthophorus_. _Archæocidaris agassizi_ Hall. _Archæocidaris trudifer_ White. _Worm._ _Fenestella shumardi_ Prout. _Fenestella remota_ Foerste. _Polypora elliptica_ Rogers. _Polypora submarginata_ Meek. _Rhombopora lepidodendroides_ Meek. _Septopora biserialis_ (Swallow) Foerste. _Septopora_ sp. _Ambocœlia planoconvexa_ (Shumard) Hall and Clarke. _Chonetes granulifer_ Owen. _Derbya crassa_ (Meek and Hayden) Waagen. _Derbya keokuk_ (Hall) Hall and Clarke. _Dielasma bovidens_ (Morton) White. _Hustedia mormoni_ (Marcou) Hall and Clarke. _Meekella striaticostata_ (Cox) White and St. John. _Orbiculoidea missouriensis_ (Shumard) Hall and Clarke. _Productus cora_ d’Orbigny. _Productus costatus_ Sowerby? de Koninck. _Productus longispinus_ Sowerby? _Productus nebraskensis_ Owen. _Productus pertenuis_ Meek. _Productus punctatus_ (Martin) Morton. _Productus semireticulatus_ (Martin) d’Orbigny. _Reticularia perplexa_ (McChesney) Schuchert. _Seminula argentia_ (Shepard) Hall and Clarke. _Spirifer cameratus_ Morton.