CARBONIFEROUS LAMELLIBRANCHIATA. 



Pinna mutica, M'Goij, 184.4. Plate I, figs. 1— G. 



Pinna mutica, M'Coy, 1844. Syuops. Carb. Foss. Ireland, p. 86, pi. xix, fig. 11. 



— IvANiSKiANA, de VemtuU, 1845. Ge'ol. Eussie d'Europe, vol. ii, p. 319, 



pi. XX, fig. 12. 



— SPATULA, M'Coy, 1853. Ann. Mag. Nat. Hist., 2nd ser., vol. xii, p. 188. 



— — Morris, 1854. Cat. Brit. Foss., 2nd edit., p. 180. 



— — — 1855. Brit. Pal. Foss., p. 499, pi. iii e, figs. 9, 10. 



Cf. — SUBSPATULATA, Worthen, 1875. Geol. Siirv. Illinois, vol. vi, p. 524, pi. xxx, 



fig. 4. 



— SPATULA, Armstrong, Young, and Robertson, 1876. Cat. West. Scott. Foss., 



p. 52. 



— — Bigsby, 1878. Thesaurus Devonico-Carboniferus, p. 293. 

 AvicuLOPiNNA SPATULA, dc Koninch, 1885. Ann. Mus. Eoy. Hist. Nat. Belg , 



torn, xi, p. 167, pi. xxvii, figs. 7 — 9. 

 — d'Orbignyi, de Konlnck, 1885. Ibid., p. 167, pi. xxvii, figs. 3, 4. 



Pinna spatula, Etheridge, 1888. Brit. Foss., pt. 1, Palaeozoic, p. 275. 



— MUTICA, Etheridge, 1888. Ibid., p. 275. 



AvicuLOPiNNA SPATULA, Tomqnist, 1896. FossiLfiihr. Untercarb. Siidvogeseu, 



Abh. geol. Specialkarte Elsass-Lothr., Band v. Heft 

 5, p. 63, pi. xvii, fig. 13. 



S])ecijic Gharaders. — Shell transversely produced, triangularly elongate, only 

 very slightly convex except near the anterior end. The anterior end is obsolete, 

 and the shell terminates in this direction in a blunt point. The posterior border 

 passes downwards and backwards, and is straight except posteriorly, where it 

 curves bluntly upwards to join the posterior margin. It is truncate, bluntly 

 rounded. The hinge-line is straight and long. The umbones appear to be obsolete 

 and terminal. The convexity of the valve becomes less and less as the expanded 

 posterior end is approached. 



Interior. — The adductor muscle is large, shallow, oval, placed on the dorsal 

 slope, remote from the posterior end, and a little below the hinge-line. There is a 

 long groove parallel to and below the superior border for the internal ligament, and 

 another broader groove just within the lower border for the anterior third of the 

 valve. The hinge-line is thin and edentulous. Interior of shell smooth. 



Exterior. — The surface is almost smooth, with very faint, broad, laminar lines of 

 growth, parallel to the margins. 



Dimensions. — PL I, fig. 1, one of the types of M'Coy's Piintn spatula, measures 

 at least 150 mm. antero-posteriorly, and 40 mm. dorso-ventrally, at the posterior 

 end. 



Localities. — England : the Carboniferous Limestone of Castleton and Park Hill, 



