BEACHIOPODS. 57 



Horizon and localities: Upper Carboniferous, Upper Coal 

 Measures : Kansas City. 



This widely distributed form is quite abundant every- 

 where along the Missouri river in Missouri, Kansas, Ne- 

 braska aud Iowa, and forms one of the most characteristic 

 species of the Upper Coal Measures. Chonetes mucronata, 

 described by Meek & Hayden, is manifestly the same species 

 with the hinge-line somewhat more extended than in Owen's 

 specimens. Chonetes smithi of Norwood and Pratten appears, 

 in all essential respects, identical with the species under con- 

 sideration. 



Orthis occidentalis HALL. 



Orthis occidentalis Hall, 1817: Pal. New York, vol. I, p. 127, pi. xxxii A, 



figs. 2a-m. 

 Orthis occidentalis Meek, 1873 : Geol. Sur. Ohio, Pal., vol. I, p. 96, pi. ix, 



figs. 3a-h. 

 Orthis occidentalis White, 1881: Geol. Sur. Indiana, 10th A.nn. Rep., p. 



486, pi. ii, figs. 10-12. 



Shell of moderate size, somewhat wider than long, trans- 

 versely subquadrate. Surface ornamented by coarse costse. 



Horizon and localities* Lower Silurian, Trenton lime- 

 stone : Cape Girardeau. 



Orthis fissicosta HALL. 



Orthis fissicosta Hall, 1847: Pal. New York, vol. I. p. 121, pi. xxxii, figs. 



7a-b. 

 Orthis fissicosta Meek, 1873: Geol. Sur. Ohio, Pal., vol. I, p. 106, pi. viii, 



figs. 6a-h. 



Like 0. retrorsa but much smaller, and with fewer and pro- 

 portionally much larger radiating costae. 



Horizon and localities. Lower Silurian, Trenton lime- 

 stone: McCune station ( Pike county ), Cape Girardeau. 



G-5 



