226 CARBONIFEROUS LAMELL1BRANCHIATA. 



Genus Pkotoschizodus, de Koninch, 1885. 



Amphidesma, PortlocJc, 1843. Eep. Geol. Londonderry, p. 438. 



— Morris, 1843. Cat. Brit. Foss., p. 77. 



Anatina (pars), M'Coy, 1815. Synops. Carb. Foss. Ireland, p. 51. 

 Amphidesma, M' 'Coy, 1845. Ibid., p. 53. 

 Axinus (pars), M'Cog, 1845. Ibid., p. 63. 

 Leptodomus, M'Cog, 1845. Ibid., p. 67. 

 Dolabra (pars), M'Coy, 1845. Ibid., p. 65. 

 Amphidesma, Brown, 1849. Illust. Foss. Concb., p. 224. 

 Dolabba (pars), de Ryclcholt, 1S52. Melanges paleontol., pt. 2, p. 82. 

 Anatina (pars), Morris, 1854. Cat. Brit. Foss., edit. 2, p. 183. 

 Axinus (pars), Morris, 1854. Ibid., p. 189. 

 Anodontopsis, Morris, 1S54. Ibid., p. 184. 

 Dolabra (pars), Morris, 1854. Ibid., p. 202. 

 Leptodomus, Morris, 1854. Ibid., p. 202. 

 Schizodus, Meek, 1871. Proc. Acad. Nat. Sci. Philad., p. 165. 

 Axinus, Young and Armstrong, 1871. Trans. Geol. Soc. Glasg., vol. iii, p. 49. 

 Niobe, de Koninch, 1873. Eeebercbes sur les Anim. foss., vol. ii, p. 77. 

 Schizodus (pars), Bigsly, 1875. Tbesaurus Devonico-Carb., p. 311. 

 Axinus, Young and Armstrong, 1S76. Cat. AY. -Scot. Foss., p. 53. 

 Peotoschizodus, de Koninck, 1SS5. Ann. Mus. Roy. Hist. Nat. Belgique, vol. xi, 



p. 125. 

 — Fischer, 1887. Mem. Concbyliologie, p. 996. 



Schizodus (pars), Etheridge, 1888. Brit. Foss., vol. i, Palaeozoic, p. 290. 

 Anodontopsis, Etheridge, 1888. Ibid., p. 278. 

 Leptodomus, Etheridge, 18S8. Ibid., p. 284. 

 Dolabra, Etheridge, 1888. Ibid., p. 283. 

 Anatina, Etheridge, 1888. Ibid., p. 277. 

 Protoschizodus, Tornquist, 1S96. Fossilf'iibr. L T ntercarb. Siidvosgesen, p. 147. 



Generic Characters. — Shell subtriangular, inequilateral, compressed, rounded 

 in front, angular posteriorly. Umbones small, subcentral, with an oblique keel 

 from the umbo to the posterior-inferior angle, closed all round. 



Hinge : the left valve with two teeth situated anteriorly, the posterior and 

 larger and most prominent being immediately below the umbo. The right valve 

 has a single tooth situated in front, with a fossa on each side to receive the teeth 

 of the left valve. 



Adductor muscle-scars shallow, close to the hinge-line. Pallial line entire. 

 Surface smooth, with fine concentric lines of growth. 



Observations. — De Koninck states that he had long had doubts as to the 

 correctness of referring the Carboniferous species included in the genus Schizodus 

 by King and others to that genus, on account of the difference in the details of 



