ANIMALS. 189 
Scuizopus opscurvs, J. Sowerby. Plate XV, figs. 23, 24. 
‘ AXINUS opscurus, J. Sow. Min. Conch., vol. iv, p. 12, pl. 314, upper figure, Dec. 1, 
1821. 
(?) Carpium, N. S., Phillips. Phil. Mag., n.s., vol. iv, p. 401, 1828. 
Axinus ogscurus, J. Sow. Sedgwick, Trans. Geol. Soc. Lond., 2d series, vol. ii, p. 119, 
1829. 
— % De la Beche, Geol. Man., p. 384, 1831; Germ. Transl., 
p. 459, 1832; 3d Eng. ed., p. 573, 1833. 
= x Phillips, Encyc. Met., vol. iv, p. 616, pl. ii, fig. 7, 1834. 
a Thomson, Outlines Min. Geol. &c., vol. 1, p. 310, 1836. 
— ae Phillips, Lardner’s Cycl., Geology, vol. i, p. 190, fig. 4, 
1837. 
(?) —  parvus, Brown. Trans. Manch. Geol. Soc., vol. i, p. 31, pl. vi, fig. 30, 1841. 
— (sp. unnamed), Brown. Op. cit., vol. 1, pl. vi, fig. 18. 
(2) —  UNDATUS 3 Op. cit., vol. i, p. 31, pl. vi, fig. 31. 
?) — — . Morris, Catalogue, p. 80, 1843. 
(?) — _ PaRvus M Loe. cit. 
—  oBscurus, J. Sowerby. Loc. cit. 
— — bb Brown, Fossil Conchology, pl. xxix, figs. 5, 6, 1843? 
(@) —  unpatus, Brown. Op. cit., pl. lxxix, fig. 9. 
— (sp. unnamed), Brown. Op. cit., pl. Ixxix, fig. 7. 
—  (Scutzopus) opscurus, J. Sow. De Verneuil, Bull. Soc. Géol. de France, 2™* 
série, vol. i, p. 31, 1844. 
@) — _ parvus, Brown. Loe. cit. 
(2) — wnpatus ,, Loc. cit. 
Qa — — i Geol. Russ., vol. i, p. 224, 1845. 
(!) —  paRvus ,, Loe. cit. 
—  osscurRus, J. Sow. Loe. cit. 
= = op Philippi, Menke’s Zeitschrift fiir Malakozoologie, p. 94, 
1845. 
ScHIzoDUS — a Tennant, Strat. List., p. 88, 1847. 
—_ PARVUS ,, Loe. cit. 
— UNDATUS ,, Loe. cit. 
Diagnosis.—“‘ Obovate, posteriorly cuneiform ; anteriorly rounded ; surface convex, 
with one obtuse keel ; 
beaks large.” (Sowerby.’) 
This well-known species is characterised with thick valves, as shown by the 
strongly-marked muscular impressions on casts (vide Pl. XV, fig. 23); a somewhat 
acuminated posterior end, caused by the ventral and dorsal margins sloping so much 
towards each other; a ee ey: -deep, rounded anterior end; and posteriorly 
twisted umbones. 
The fossils which Captain Brown has placed in the genus Avinus appear to me to 
be referable to two species only, one of which I consider synonymous with Schizodus 
1 Mineral Conchology, vol. iv, p. 12. 
