SCHIZODUS. 213 



Schizodus, Salter, 1860. Trans. Royal Soc. Edin., vol. xxii, p. 385. 



— — 1861. Mem. Geo], Surv. Gfc. Brit., " Iron Ores Gt. Brit.," 



pt. 3, pi. i, fig. 30, p. 221. 

 Cypricardia ?, Swallow, 1862. Trans. St. Louis Acad., vol. i, p. 96. 

 Schizodus, Meek and Worthen, 1865. Proc. Acad. Nat. Sci. Phil., p. 457. 



— Meek and Ilayden, 1865. Pal. of Upper Missouri, p. 58. 



— Meek and Worthen, 1866. Proc. Chicago Acad. Nat. Sci., vol. i, p. 18. 



— — — Geol. Surv. Illinois, vol. ii, p. 301. 

 Geinitz, 1866. Carbon und Dyas in Nebraska, p. 18. 



Meek and Worthen, 1870. Proc. Acad. Nat. Sci. Phil., p. 41. 



— Stoliczka, 1881. Pal. Indica Cret. Faun., vol. iii, p. 309. 

 Non Meek, 1871. Proc. Acad. N. Sci. Phil, p. 165. 



„ Axinus, Young and Armstrong, 1871. Trans. Geol. Soc. Glasg., vol. iii, Appendix, 



p. 49. 

 Schizodus, Meek and Worthen, 1873. Geol. Surv. Illinois, vol. v, p. 579. 

 White, 1875. Rep. Exp. W. of 100th Merid., vol. iv, p. 154. 



— Meek, 1875. Rep. Geol. Surv. Ohio, vol. ii, pt. 2, p. 336. 



— JR. Etheridge,jun., 1875. Ann. Mag. Nat. Hist., ser. 4, vol. xv, p. 431. 

 Axinus (pars), Young and Armstrong, 1876. Carb. Eoss. W. of Scotland, p. 53. 

 Schizodus, E. Etheridge.jun., 1878. Quart. Jouru. Geol. Soc, vol. xxxiv, p. 15. 



— Bigsbg, 1878. Thesaurus Devonico-carboniferus, p. 311. 



— Barrois, 1882. Terr, anciens des Asturias et de la Galice, p. 341. 

 White. U.S. Geol. Surv. Indiana, 13th Ann. Rep., p. 147. 



— Walcott, 1884. Mon. U.S. Geol. Surv. Pal. Eureka District, p. 252. 



— Fischer, 1887. Manuel de Conch., p. 995. 



— Waagen, 1887. Pal. Indica, ser. xiii, vol. i, " Salt Range Eossils," p. 230. 



— Etheridge, 1888. Brit. Foss., vol. i, Palaeozoic, p. 290. 



— Miller, 1889. N. Amer. Geol. and Pal., p. 510. 



Ward, 1890. Trans. N. Staff. lust. Min. and Mech. Eug., vol. x, 

 p. 131. 



— Worthen, 1890. Geol. Surv. Illinois, vol. viii, p. 107. 

 Nucula, sp., Wild, 1891. Trans. Manch. Geol. Soc, vol. xxi, pi. ii, fig. 3. 

 Scuizodus, Miller, 1891. Geol. Surv. Indiana, 17th Ann. Pep., p. 91. 



— Whitfield, 1893. Rep. Geol. Surv. Ohio, vol. vii, p. 474. 



— Wuhrman, 1894. Jahrbuch k. k. Geol. Reichsanstalt, Band xliii, p. 7. 



— Keges, 1894. Missouri Geol. Surv., vol. v, pt. 2, p. 123. 



Generic Characters. — Bquivalve, inequilateral, the posterior side produced. 

 Ovate, trigonal, gibbose. The hinge consists of three teeth in each valve, 1:1:1, 

 those of the right valve being anterior to those in the left. Adductor muscle- 

 scars well marked but shallow. Pallial line entire. 



Surface smooth, or with fine concentric parallel lines, which have the same 

 contour as the margins. 



Observations. — Professor King, as early as 1844 {op. supra cit.), stated that he 

 proposed to institute the generic term " Schizodus for the Permian and Car- 

 boniferous Axinuses, to distinguish them from the London C\&y Axinus angulatus." 



