BRACHIOPODS. 103 



Rhynchonella mutata HALL. 



RhynchoneUa mutata Hall, 1856 i Trans. Albany Institute, vol. IV, p. 10. 

 Rhynchonella mutata Hall, 1858: Geology Iowa, vol. I, p. 658, pi. xxiii, 

 figs. 2a-b. 



A small form like E. subcuneata, but smaller and less 

 cuneate. 



Horizon and localities. Lower Carboniferous, Keokuk 

 limestone : Boonville. 



Rhynchonella ottumwa WHITE. 



Rhynchonella ottumwa White, 1883: 12th Ann. Rep. U. S. Geol. and 

 Geog. Sur. Terr., p. 165, pi. xli, figs. 5a-c. 



Similar to R. uta, but with mesial sinus much less pro- 

 nounced. 



Horizon and localities. Lower Carboniferous, Saint Louis 

 limestone : near St. Francisville ( Clark county). 



Rhynchonella uta (MARCOU). 



Plate xli, fig. 7. 



Terebratula uta Marcou. 1858 : Geol. N. A., p. 51, pi. vi, figs. 21a-c. 

 Rhynchonella (Camarophoria) osagensis Swallow, 1858: Trans. St.'Louis 



Acad. Sci., vol. I, p. 219 

 Camarophoria swallowiana Shumard, 1858: Trans. St. Louis Acad. Sci., 



vol. I, p. 34, pi. xi, figs. la-e. 

 Camarophoria globulina Geinitz, 1866: Carb. und Dyas in Nebraska, p. 38, 



tab. iii, fig. 5 (Not C. globulina Phillips, 1834.) 

 Rhynchonella osagensis Meek, 1872: U. S. Geol. Sur. Nebraska, p. 179, 



pl.i, figs. 9a-b; and pi. vi, figs. 2a-b. 

 Rhynchonella osagensis Meek & Worthen, 1873 : Geol. Sur. Illinois, vol. V, 



p. 571, pi. xxvii, fig. 22. 

 Rhynchonella uta White, 1875 : U.S. Geog. Sur. w. 100 Merid , vol. IV, 



p. 128, pi. ix, figs. 2a-c. 



Shell small, subtrigonal in outline, slightly wider than long, 

 more or less ventricose. Ventral valve not as convex as the 

 other one ; medial sinus short but well denned ; beak pointed, 

 not very prominent ; foramen small. The median sinus is oc- 

 cupied by two to three sharply angular plications ; and each of 

 the lateral lobes by about three similar short ridges. Dorsal 

 valve much more arched than the ventral ; median fold rather 

 low, not defined behind the middle of the shell, marked by two 



