428 CARBONIFEROUS LAMELLIBRANCHIATA. 



Allorisma Ansticei, Sowerby, sp., 1840. Plate XLIX, figs. 1 — 3. 



Unio Ansticei, Sowerby, 1840. Trans. Geo). Soc, ser. 2, vol. v, pt. 3; Geol. 



Coalbrookdale, Appendix, pp. 491 and 501, 

 pi. xxxix, fig. 7. 

 — ? — Morris, 1843. Cat. Brit. Fobs., 1st. edit., p. 105. 

 Sanguinolites contoetus, irCoy, 1844. Synops. Carb. Foss. Ireland, p. 48, 



pi. xix, fig. 3. 

 Unio Ansticei, Brown, 1849. lUust. Foss. Couch., p. ISO, pi. Ixsxviii, figs. 



25, 27. 

 ^Myacites Ansticei, Morris, 1854. Cat. Brit. Foss^., 2ud edit., p. 213. 

 Sanguinoi.ites contoetus, Morris, 1854. Ibid., p. 223. 



— — Biffsby, 1877. The.^iaurus Devonico - Carbouiferus, 



p. 311. 

 Alloeisma Ansticei, Bigsby, 1877. Ibid., p. 295. 



Myacites Ansticei, Bthcridrje, 18S8. Brit. Foss., pt. 1, Paleozoic, p. 286. 

 Sanguinolites contoetus, Etheridge, 1888. Ibid., p. 289. 



Specific Character's. — Shell of medium size, transversely oblong, compressed, 

 obliquely tumid, very inequilateral, not carinate. The anterior end short, much 

 narrowed from above downwards by the rapid descent of its upper border, and 

 moderately convex, its margin bluntly rounded. The antero-inferior angle pro- 

 jects forward. The inferior margin is almost straight, with a sinuosity at about 

 its centre, but becoming convex posteriorly, where it is curved bluntly upwards 

 to pass into the posterior margin. The latter is obliquely truncate from above 

 downwards and backwards, and is straight above but rounded obtusely below. 

 'J^he postero-superior angle is well marked and obtuse. The hinge-line is depressed, 

 curved in front, prolonged and straight behind. The umbones are of moderate 

 size, obliquely swollen, incurved, pointed, contiguous, raised above the hinge-line, 

 and placed at the junction of the anterior and middle thirds of the valve. Passing 

 downwards and backwards from the umbones towards the postero-inferior angle 

 is an oblique gibbosity, narrow and well marked above, but becoming broader and 

 less conspicuous as it passes across the valve. An erect curved ridge passes from 

 the extreme point of the umbo backwards, and terminates at the postero-superior 

 angle, separating the escutcheon from the dorsal slope. 



In front of the oblique gibbosity the valve is much compressed, giving rise to 

 a well-marked lateral sinus, which is narrow above but becomes broader and 

 deeper as it approaches the infei'ior margin. The oblique gibbosity passes 

 gradually into the dorsal slope, which is of moderate size, compressed, and 

 hollowed. The lunule is large, deep, and elongate. The escutcheon is broad, 

 shallow, and elongate. 



