CARDIOMORPHA CORRUGATA. 271 



showing the hinge-plate or the interior. The shape and markedly prosogyrous 

 umbones are, however, very typical of the genus. This species never appears to 

 attain to any considerable size, fig. 21, PI. XIX, being the largest specimen I 

 have yet obtained. Fig. 17, PL XXI, is the only specimen with both valves in 

 contact which I have yet seen. I figure also a series showing the shell in all 

 stages of growth from a very small size to the full-grown adult. 



De Koninck, in his ' Description des animaux fossiles,' &c, p. 100, described 

 a species, apparently of Cardiomorpha, under the name of Isocardia pumila, which 

 agrees with G. parva in its' small size, but has its dorso-ventral diameter greater 

 than the transverse. This species has been lost sight of, and is not redescribed 

 in de Koninck's later work, so that it has been impossible for me to examine the 

 specimen. The species was founded on two specimens from the Limestone of Vise. 



From the only other small species of this genus (Gardiomorpha limosa), G. parva 

 can at once be distinguished by its less transverse and more globose shape. 



I do not think it probable that we have to do here with a dwarfed form of 

 one of the larger species of Cardiomorpha, though in shape it very closely 

 resembles G. orbicularis, M'Coy. Other dwarfed forms of species associated with 

 the latter shell are not found in the Redesdale fauna, which, especially with 

 regard to the bivalves, is very different from that which is found in the Carbo- 

 niferous Limestone. Both species, however, occur at horizons which have beds 

 containing Productus giganteus both above and below them. 



Cardiomorpha corrogata, M'Coy, 1844. Plate XXIII, figs. 5 — 7. 



Cardiomorpha. corrugata, M'Coy, 1S44. Synops. Carb. Foss. Ireland, p. 56, 



pi. viii, fig. 15. 



— — d'Orbigny, 1850. Prod. Pal. Strat, vol. i, p. 133. 



— — Morris, 1854. Cat. Brit. Foss., 2nd edit., p. 190. 



— — Griffith, 1860. Journ. Greol. Soc. Dublin, vol. ix, 



p. 91. 

 Isoculia corrtjgata, M'Coy, 1862. Synops. Carb. Foss. Ireland, 2nd edit., pi. viii, 



fig. 15. 

 Cardiomorpha corkugata, Biysly, 1878. Thesaurus Devonico-Carbonif., p. 301. 

 Isoculia corrugata, de Koninck, 1885. Ann. Mus. Roy. Hist. Nat. Belgique, 



vol. xi, p. 18, pi. viii, fig. 5 ; pi. ix, 

 figs. 5—9. 

 ? — undata, de Koninck, 1SS5. Ibid., p. 18, pi. x, figs. 3, 27, 28. 

 Cardiomorpha corrugata, Etheridye, 1888. Brit. Foss., vol. i, Palseoz., p. 280. 



Specific Characters. — Shell large, gibbose, slightly transverse, obliquely sub- 

 orbicular. The anterior end is shorter and compressed, especially at the 



