228 CARBONIFEROUS LAMELLTBRANCHIATA. 



I am referring the Leptodomus fragilis, M'Coy, to Protosehizodus. Leptodomus, 

 as first defined, was very unsatisfactory, containing the shell mentioned above and 

 Leptodomus (Corbula) senilis, Phillips, which is really an Edmondia. Later on 

 (' Brit. Pal. Foss.,' p. 277) Leptodomus was emended by M'Coy in such a way as 

 would exclude both his original species. Many of the shells described by 

 M'Coy under the generic name Axinus I have now placed under Protosehizodus; 

 three out of the four new species described by him as Axinus being retained. 



King pointed out in a foot-note (' Permian Fossils,' p. 185) that he thought 

 Sedgwickia gigantea of M'Coy was a species of Schizodus, and that "the same may 

 be said of Leptodomus fragilis, M'Coy; Dolabra securiformis, M'Coy; Mactra 

 ovata, M'Coy; Amphidesma subtruncata, M'Coy; Anatina deltoidea, M'Coy; 

 Axinus obliquus, M'Coy, &c." To a certain extent King was correct in his 

 view, for the majority of these shells belong to the same genus, which is now 

 separated from Schizodus, since de Koninck pointed out the essential differences 

 in the structure of the hinge. I propose still to retain the genus Sedgwickia, to 

 which Dolabra securiformis probably belongs. 



Pkotoschizodus axinifoemis, Portloclc, sp., 1843. Plate XVII, figs. 10, 13, 14, 



10— 19. 



Venus ? caebonaeia, Portloclc, 1813. Rep. Geol. Londonderry, p. 438. 

 Amphidesma caebonaeia, Portloclc, 1843. Ibid., pi. xxxvi, fig. 8. 



— depeessa, Portloclc, 1813. Ibid., p. 439. 



— axinifoemis, Portloclc, 1843. Ibid., p. 439, pi. xxxvi, fig. G. 



— deltoidea, Portloclc, 1813. Ibid., p. 439, pi. xxxvi, fig. 7. 



— caebonaeia (pars), Morris, 1843. Cat. Brit. Foss., p. 77. 



— axinifoemis, Morris, 1S43. Ibid., p. 77. 



— depeessa, Morris, 1843. Ibid., p. 77. 



Axinus axinifoemis, M'Coy, 1844. Synops. Carb. Foss. Ireland, p. 63. 



— caebonaeius, M'Coy, 1841. Ibid., p. 63. 



— deltoideus, M'Coy, 1844. Ibid., p. 63. 



Amphidesma Pobtlockii, Brown, 1849. Illus. Foss. Conch., p. 224, pi. xci, 



fig. 40. 



— axinifoeme, 1 Brown, 1849. Ibid., fig. 41. 

 Cxpeicaedia deltoidea, Broicn, 1S49. Ibid., pi. lxxx, fig. 6. 



Axinus axinifoemis (pars), Morris, 1854. Cat. Brit. Foss., 2nd edit., p. 188. 



— caebonaiuus (pars), Morris, 1854. Ibid., p. 189. 



— deltoideus (pars), Morris, 1854. Ibid., p. 1S9. 



— caebonaeius, Young and Armstrong, 1871. Trans. Geol. Soc. Glasgow, 



vol. iii, Appendix, p. 50. 



1 The other specific names of Amphidesma ought also to be neuter words, because Mo^a is 

 neuter. 



